Dissertations / Theses on the topic 'Wind ventilation'
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Luo, Zhiwen, and 罗志文. "City ventilation by slope wind." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B46089962.
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Wang, Bo. "Unsteady wind effects on natural ventilation." Thesis, University of Nottingham, 2010. http://eprints.nottingham.ac.uk/11653/.
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Ventilation stacks are becoming increasingly common in the design of naturally ventilated buildings. The overall aim of the work described is ultimately to improve design procedures for such buildings. This thesis presents the experimental and theoretical investigation of unsteady wind effects on natural ventilation of a single envelope with multiple openings for both wind alone, and wind and buoyancy combined cases. There are two types of openings: namely the sharp-edged orifice and the long opening (stacks being treated as long openings). Two methods are adopted: 1) direct wind tunnel measurements using the hot-wire technique; 2) theoretical analysis using steady and unsteady envelope flow models. For the wind alone experiments, the influences of wind speed, wind direction and opening configuration on flow patterns are studied. For the wind and buoyancy combined tests, the transitional process between wind dominated and buoyancy dominated states are investigated. The direct velocity measurements provide the criteria for testing the validity of the theoretical models, and ways to improve them. Additionally, improvements are made to the experimental techniques: e.g. a precise unsteady calibration method of the hot-wire is developed; improvements of pressure measurements are also investigated. The experimental technique works well with multiple stacks. Even though small openings are used, some dependence of the mean pressure coefficient on opening configuration is observed. The theoretical models also work reasonably well with multiple stacks, yet it is observed that the accuracy of the theoretical models decrease with the increasing number of openings, and is sensitive to the chosen discharge coefficient which defines the characteristics of ventilation openings.
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Al-Qahtani, Turki Haif. "An improved design of wind towers for wind induced natural ventilation." Thesis, University of Bath, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323566.
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Straw, Matthew Peter. "Computation and measurement of wind induced ventilation." Thesis, University of Nottingham, 2000. http://eprints.nottingham.ac.uk/10110/.
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This thesis aims to predict wind induced ventilation of a structure through the application of current analytical techniques, computational fluid dynamics simulations and novel techniques for ventilation flows induced by turbulent mechanisms. Validation of the predictions was carried out through full-scale measurements undertaken on a purpose built test structure. The structure was of cubic design with an external dimension of 6m. The construction of this full-scale research structure at Silsoe Research Institute, Bedfordshire, England, provided a unique opportunity for undertaking full-scale experimentation on a fundamental wind engineering test case which, prior to this thesis, had only been investigated using scale models in wind tunnels and computational simulations.
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Chaplin, G. C. "Turbulent wind interactions with ventilated structures." Thesis, University of Nottingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339663.
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Hang, Jian, and 杭建. "Wind conditions and urban ventilation in idealized city models." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B42841471.
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Hang, Jian. "Wind conditions and urban ventilation in idealized city models." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B42841471.
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Bensalem, Rafik. "Wind driven natural ventilation in courtyard and atrium-type buildings." Thesis, University of Sheffield, 1991. http://etheses.whiterose.ac.uk/3000/.
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This study investigated the effectiveness of wind-driven natural ventilation in courtyard and atrium-type buildings, particularly in the context of ventilative cooling. Courtyard and atrium buildings are currently enjoying great popularity. Perhaps a primary reason for their revival comes from the energy and environmental awareness of the current period, in which courtyard and atrium concepts are emerging as very promising. Wind-driven ventilation is one of the most basic and probably among the most efficient ways to prevent overheating, and provide cooling in the summer season, especially in humid climates. A review of previous works showed that little attention has been given to the wind-driven natural ventilation capability of these structures, and to the means of maximizing this ventilation. This study was thus aimed to fill part of the gap in this subject. In order to evaluate the wind-driven ventilation effectiveness of these structures, and to examine some of the influential parameters, experimental wind tunnel tests were made. Actual indoor air flows were measured in small replica models of four-storey courtyard and atrium buildings by means of small calibrated orifice plates. A parametric study of the geometry of the courtyard was made in isolation conditions, where the depth and breadth of the courtyard were systematically varied. Several atrium ventilation modes were tested both in isolation and in urban terrains. The tests involved different roof geometries and various roof porosities. The measurements were followed by a discussion on the validity of simple computational methods to predict airflow in atria. The investigation portrayed the importance of some factors, such as the wind orientation rather than the courtyard geometry, for enhancing the flow in these structures. The superiority of some atrium designs over the courtyard types, particularly in sheltered sites, was underlined. The study concluded with a discussion of design guide-lines and referred the reader to an application as an example, describing a simple step-by-step method to estimate the cooling benefits of these structures in a particular site, and making use of the measurement data obtained from the study.
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Carey, P. S. "Direct wind tunnel modelling of natural ventilation for design purposes." Thesis, University of Nottingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422325.
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Lishman, Ben Stanley Roy. "The control of natural ventilation with opposing wind and buoyancy." Thesis, University of Cambridge, 2007. https://researchportal.port.ac.uk/portal/en/theses/the-control-of-natural-ventilation-with-opposing-wind-and-buoyancy(97d0423b-9083-4078-bd8c-009141a8559e).html.
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This thesis is an investigation of the control of naturally ventilated buildings subject to opposing wind and buoyancy. Previous research shows that the interaction of wind and buoyancy can lead to complicated behaviour, and that this in turn can make it difficult to design controllers for naturally ventilated buildings. The aim of this research is therefore to aid in the design of such controllers.
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Farija, Ghassan Mahmood. "Wind induced natural ventilation for wind tower houses in maritime desert climates with special reference to Bahrain." Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270325.
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Tavakolinia, Fereshteh. "Wind- Chimney (Integrating the Principles of a Wind-Catcher and a Solar-Chimney to Provide Natural Ventilation)." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/678.
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WIND-CHIMNEY
Integrating the principles of a wind-catcher and a solar chimney to provide natural ventilation
Fereshteh Tavakolinia
Abstract
This paper suggests using a wind-catcher integrated with a solar-chimney in a single story building so that the resident might benefit from natural ventilation, a passive cooling system, and heating strategies; it would also help to decrease energy use, CO2 emissions, and pollution. This system is able to remove undesirable interior heat pollution from a building and provide thermal comfort for the occupant.The present study introduces the use of a solar-chimney with an underground air channel combined with a wind-catcher, all as part of one device. Both the wind-catcher and solar chimney concepts used for improving a room’s natural ventilation are individually and analytically studied. This paper shows that the solar-chimney can be completely used to control and improve the underground cooling system during the day without any electricity. With a proper design, the solar-chimney can provide a thermally comfortable indoor environment for many hours during hot summers. The end product of this thesis research is a natural ventilation system and techniques that improve air quality and thermal comfort levels in a single story building. The proposed wind-chimney could eventually be designed for use in commercial, retail, and multi-story buildings.
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Pinnock, David J. "An investigation into the influence of wind in single-sided natural ventilation." Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/7465.
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In the present energy and CO2 emission conscious climate natural ventilation is undergoing increasingly intensive research. Buildings located in a sheltered in-fill location subject to single-sided natural ventilation are a common occurrence. However, the combination of stack effect and wind effect induced natural ventilation rates is not well defined. This thesis investigates the influence of wind on a sheltered building subject to single-sided natural ventilation. Full-scale experiments were undertaken over a wide variety of prevailing conditions on a suitable test cell to provide the measurements for the investigation. The analysis established that the flow/pressure drop relationship representing the airflow across the boundary of the building was best described by a power law relationship with an index of n=0.6348, rather than the conventional Bernoulli equation (which reflects a special case of the power law relationship when the index n=0.5). "Warren" plots, modified to reflect the power law flow/pressure drop relationship, identified stack effect dominance for the test cell. However, the wind was shown to influence the single-sided natural ventilation rates by virtue of the wind direction altering the flow path through the openings in the building and, so, affecting the flow characteristics of the openings. The investigation enabled a prediction model to be developed whereby the natural ventilation rates in the test cell subject to single-sided natural ventilation could be predicted from internal and external temperature and wind direction. Validation of the model identified an over-prediction for high stack effect driving forces and underprediction for low driving forces. The over- and under-prediction was concluded to be the result of incorporating the flow characteristics of the building openings as constant values. The flow characteristics should be treated as a variable function of wind direction and the stack effect driving force.
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Hult, Erin L. (Erin Luelle) 1982. "Experimental simulation of wind driven cross-ventilation in a naturally ventilated building." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32808.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.Includes bibliographical references (p. 29).
A device was designed and constructed to simulate cross-ventilation through a building due to natural wind. The wind driver device was designed for use with a one tenth scale model of an open floor plan office building in Luton, England. The air flow patterns produced by the wind driver were observed, and the uniformity of the velocity of the flows into the model windows was measured for the three settings of the wind driver fans. The temperatures and velocities of flows on the interior of the building and at the exhaust windows were also examined. The wind driver device was capable of producing uniform velocities across the face of the model to within 20 to 27%, depending on the fan setting. The consistency of certain features of the velocity distributions produced by the wind driver operating at different speeds suggest that improvements made to the design of the wind driver could lower this variation to about 15%. The velocities measured on the interior of the model seem consistent with interior velocities in the Luton building, although further experimentation is needed to confirm this trend. Cross-ventilation was effective in reducing interior model temperatures by up to 10⁰C from the natural convection case.
by Erin L. Hult.
S.B.
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Brown, Melissa E. "The Union of Aerial and Terrestrial Forces." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/35404.
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Environmentally sensitive architecture is rapidly staking its claim on the building community. The structures that are being constructed to fulfill the increasing public demand for "green buildings" are not currently utilizing their unique potential to physically portray their inherent characteristics to be naturally and technologically advanced. Environmentally sensitive architecture has the potential and arguable responsibility to physically react to and portray the natural factors that they are programmatically and technically adapting to.Master of Architecture
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Elzaidabi, Abdalla Ali Mohamed. "Low energy, wind catcher assisted indirect-evaporative cooling system for building applications." Thesis, University of Nottingham, 2009. http://eprints.nottingham.ac.uk/10703/.
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Increased consciousness of the environmental problems has aroused people’s interest of renewable energy systems, especially the application of green features in buildings. The demand for air conditioning / cooling in domestic and non-domestic buildings is rising throughout the world; this increases the reliance on conventional fuels and the global warming effect from greenhouse gas emissions. Passive cooling and energy efficient design can substantially reduce reliance on fuel based heating and cooling. Passive and Hybrid Downdraught Cooling, in different forms, is now technically viable in many parts of the world. This has been established through a combination of research projects. In some hot arid regions, a major part of the energy consumed consists of air-conditioning requirements. Alternative methods, using passive cooling techniques, can assist in reducing the conventional energy consumption in buildings. Evaporative cooling, which can be tracked back several hundreds of years in ancient Egypt and Persia [1–3], is one of the most effective strategies, because of the enormous latent heat needed for evaporation of water. Green features are architectural features used to mitigate migration of various air-borne pollutants and transmission of air from outside to indoor environment in an advantageous way [9]. The reduction of fossil fuel consumption and the associated decrease in greenhouse gas emissions are vital to combat global warming and this can be accomplished, in part, by the use of natural ventilation. To assess the performance of several innovative cooling systems devices and to develop improved models for more established technology, quantitative measurement of output was necessary. This was achieved in this study by the development of simply constructed low energy cooling systems which were calibrated by the innovative use of wind and water as a source. These devices were found to be consistent and accurate in measuring the temperature and cooling load from a number of devices. There were some problems in the original evaporative units. Therefore, a number of modifications have to be made to enhance the systems performance. The novel Windcatcher – PEC cooling system was assessed and different cooling loads were achieved.
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Gomaa, Bakr M. "Wind channels : a novel passive ventilation system for deep plan high-rise residential buildings." Thesis, University of Nottingham, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546571.
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Cheng, Charles Chor Kwan. "Wind-induced natural ventilation of the refuge floor of a high-rise building in Hong Kong." Queensland University of Technology, 2006. http://eprints.qut.edu.au/16400/.
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An important element in the building fire safety of high-rise buildings in Hong Kong since 1996 has been the use of refuge floors in the building's evacuation system. To prevent smoke collecting and remaining in the refuge floors, the Building Code of Hong Kong requires these floors to have openings on opposite sides to provide adequate wind-induced ventilation. Other researchers using CFD simulations without wind tunnel verification have indicated that under certain conditions smoke could still remain on these floors and thereby reducing the fire safety of the refuge floors. This thesis explores these situations and presents a detailed scientific investigation of the wind movement in and around a refuge floor at mid-height of a high-rise building using wind tunnel testing together with CFD simulations (using CFD CFX-5.6 package). Besides identifying problem areas for smoke logging, this thesis also identifies how the design of a refuge floor can be modified to improve its fire safety. A significant factor on the fire safety of a refuge floor is the blocking effect of the building's central core and its effect on the wind-induced ventilation. Under Hong Kong Building Code, the central core can occupy up to 50% of the refuge floor. Previous investigators did not take into consideration the effect of the maximum core size on natural ventilation of the refuge floor. This thesis investigates the worst case scenario for a refuge floor that has a core occupying 50% of the floor and has two solid walls on opposite side of the floor to identify the problem areas where smoke could collect and remain. In exploring the worst case scenario with two parallel solid walls, the investigations revealed that the ceiling height and the wind direction have a significant effect on the wind ventilation of the refuge floor. These factors were not identified by previous investigators. In the case of the ceiling height, it was found that the head height of the refuge floor should be greater than 0.02 times the building height to achieve the desirable wind environment on the refuge floor. Regarding wind directions, the wind from most angles escapes the floor via the channel-like corridors next to the central core of the building. The main problem area occurred when the wind was perpendicular to the solid side walls. This resulted in noticeable stagnant areas where smoke could remain. To validate the CFD method used in the thesis, wind tunnel experiments were performed to provide the scientific field velocity data of wind flowing over the building and in the refuge floor located at mid-height of the building. Earlier researchers of the refuge floor did not have access to wind tunnel data of a refuge floor. In comparing the wind tunnel experiments with the CFD simulations used in the thesis, acceptable agreement was achieved. These results make it possible for a significant reduction in the CFD computational effort that previous studies required. Based on the findings of the investigations undertaken, design recommendations are proposed to improve the fire safety of the refuge floor in multistorey buildings in Hong Kong.
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Radosavljevic, Dejan. "The numerical simulation of direct-contact natural-draught cooling tower performance under the influence of cross-wind." Thesis, Imperial College London, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261786.
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Katyarmal, Preeti P. "Light, Shadow and Wind in Building Design." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/30980.
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Design is about understanding a space.
It is about integration of light and air in building design.
It is about light, shadow, reflection.
It is about wind, its movement and escape.
Through designing this project I was able to explore how sun, wind and light can be used effectively in a building design, in my project, in an office environment.
The fire, the Light; the energy is the inspiration behind the origin of Architecture. Energy brings architecture into the world of processes and life and Architecture brings together Fire and Shelter, Chaos and Organization. Day lighting or the use of natural light in a building is one of the fundamental elements used to bring an essential experience of visual comfort and outside world environmental stimulation for all building occupants.
The History of Architecture, said Le Corbusier, is a history of the struggle for light, the struggle for the window.
This thesis assembles the research, conceptualization and final development of the office building design with an integration of light and wind.Master of Architecture
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Ismail, Ab Majid. "Wind-driven natural ventilation in high-rise office buildings with special reference to the hot-humid climate of Malaysia." Thesis, Cardiff University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247267.
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O'Sullivan, Paul D. "Experimental study of single sided ventilation through a multi-configuration slotted louvre system." Thesis, Brunel University, 2018. http://bura.brunel.ac.uk/handle/2438/16416.
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Evidence based performance of novel ventilation systems in existing low energy buildings is invaluable as it provides data on the system operation in a real dynamic environment. This thesis presents the outcomes from research involving a number of experimental field studies of a single sided ventilation system installed in a single cell office space as part of a building retrofit pilot project in Cork, Ireland. The solution consists of a purpose provided, multi configuration opening, comprising a narrow slotted architectural louvre component split across a low level manual opening section and a high level automated opening section. A review of published research found that little experimental data exists on the performance of such systems and air flow rate correlations developed for plain openings are currently used by designers to make predictions about their performance. Three experimental campaigns were designed and carried out. First, in order to quantify performance of the system, long term and short term monitoring of the internal thermal and air flow environment at the experimental building was completed. Second, ventilation rate measurements in existing and retrofit spaces were completed using a tracer gas concentration decay technique. Thirdly, air flow through the single sided slot louvre opening was investigated. In addition, the annual cooling potential of the multi-configuration system was investigated computationally. Results show there was a significant difference between both thermal environments with the retrofit space consistently displaying lower air temperatures over the cooling season and throughout all Air Change Rate measurement periods. Lower levels of vertical thermal stratification and diurnal temperature variation were also observed. On average, across a wide range of boundary conditions, lower ventilation rates were observed for the slotted louvre system with a narrower spread of values when compared with the existing building. The dominant driving force was either buoyancy or wind depending on the opening configuration adopted in the slotted louvre system. The slot louvre was found to be wind dominant for lower opening heights when compared with a plain opening of the same dimensions. Existing single sided correlations were found to perform better when predicting airflow rates through a plain opening when compared with the slot louvre system and a new dimensionless exchange rate parameter is proposed for predicting wind driven airflow through the slot louvre. Simulations indicate that 80% of annual occupied hours required an enhanced ventilative cooling airflow rate to achieve internal thermal comfort. Using a combination of configurations the system was able to provide the required cooling airflow rate for 93% of the occupied hours.
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Ferrucci, Margherita. "Ventilation naturelle en architecture : méthodes, outils et règles de conception." Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1080.
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La ventilation naturelle est une stratégie passive qui permet l'échange naturel d'air entre le bâtiment et l'environnement extérieur. Elle assure une bonne qualité de l'air intérieur, améliore le confort thermique et elle réduit les besoins énergétiques, les émissions de gaz à effet de serre et les symptômes liés au syndrome du bâtiment malsain. Bien que les avantages et les bénéfices de la ventilation naturelle soient multiples, son usage est rare dans l'architecture contemporaine. Bien sûr, il existe des limites à sa mise en œuvre dans certains bâtiments, comme la mauvaise qualité de l'air extérieur, mais ces problèmes ne justifient pas une utilisation si peu répandue. La cause de sa faible diffusion est principalement liée à la difficulté de la conception plutôt que aux facteurs physiques liés à l'environnement. La thèse vise à fournir différents outils pour comprendre la dynamique des fluides dans les bâtiments et développer des techniques et des méthodes pour aider la conception des bâtiments ventilés naturellement. L'approche adoptée dans la thèse est modélisée selon les besoins du concepteur qui peut choisir d'utiliser différents types de supports tels que: utiliser des outils graphiques ou des modélisations numériques, s'inspirer de l'architecture contemporaine et répéter les solutions technologiques existantes, utiliser des outils de modélisation physique, s'inspirer du passé ou du monde naturel. Ici plusieurs aspects de la ventilation naturelle sont traités en apportant à chacun une contribution innovante afin de créer des outils d'aide pour différents phases de la conception : Les objectifs de la thèse sont de créer des outils innovants qui simplifient la conception à des niveaux différents. Nous avons créé donc, des outils et des modèles graphiques simplifiés pour choisir la forme du bâtiment et son orientation, des lignes directrices pour le dimensionnement des dispositifs de ventilation (cheminées de toit), des méthodes expérimentales simplifiées associées à des codes de lecture des écoulements d'air. Nous avons également élargit le panorama culturel et historiques et nous avons créé des indications morphologiques dérivant de l'analyse de l'architecture biomimétique. Grâce à une analyse CFD paramétrique, des outils graphiques sont générés pour évaluer, de manière comparative, les performances de ventilation d'une famille morphologique de bâtiments et choisir la forme du bâtiment, son orientation et la position des ouvertures. Nous créons des lignes directrices pour la conception et le pré-dimensionnement des dispositifs de ventilation. Les règles sont déterminées par une analyse comparative de neuf projets de bâtiments contemporains ventilés naturellement dans lesquels le dispositif de ventilation est présent. Une soufflerie est conçue et réalisée pour simplifier les visualisations des écoulements d'air autour des modèles de bâtiments et nous proposons une méthode pour réaliser des expérimentations de support à la conception. Le système de refroidissement géothermique d'une ancienne villa à Costozza (Vicence, Italie) est étudié. Cette section élargit la connaissance du patrimoine architectural italien et souligne l'importance de redécouvrir des solutions technologiques bioclimatiques existantes, toujours en fonction. On analyse une structure animale: le nid d'un insecte. Il s'agit d'un archétype bioclimatique qu'il peut être utilisé dans l'architecture en tant que technologie biomimétiqueNatural ventilation is a passive ventilation strategy of confined spaces that consists of natural air exchange between the building and the outdoor environment. Natural ventilation ensures a good indoor air quality, it improves the thermal comfort and it reduces the greenhouses gases emission, the energy demand and the symptoms associated with the Sick Building Syndrome. Although the advantages and benefits of natural ventilation are multiple, its application is rare to contemporary architecture. By the way, there are some limits to its implementation, such as the bad quality of outdoor air, but that does not justify a so limited design of naturally ventilated buildings. The cause of its rare diffusion is primarily the difficulty of design rather than the factors related to the environment. The thesis intends to provide multiple tools for understanding the fluid dynamics in buildings and to develop techniques and methods to support the design of naturally ventilated buildings. The approach adopted in the thesis is modeled according to the needs of the designer. In fact, a designer can choose to use different types of support tools such as: use of graphic tools or numerical models, inspiration to contemporary architecture to provide the existing technology solutions, use of physical modeling tools, inspiration to the past or to the nature. Often, the design is a global process and does not need a single tool but the designer uses more than one. Here, several aspects of natural ventilation are dealt with, trying to make an innovative contribution to each of these themes, in particular : Through a parametric CFD analysis, graphical tools are generated to evaluate, adopting a comparative approach, the ventilative performance of a morphological family of buildings and to choose the shape of the building, its orientation and the position of the openings. Guidelines are set for the design and pre-dimensioning of ventilation devices. The rules are determined by a comparative analysis of nine contemporary ventilation projects in which the ventilation device is present. An optimized wind tunnel is created to simplify airflow visualizations around building models. We provide also a method to make simplified experimentations, an aiding-design tool, and a code that allows to understand the views with the smoke. We study the geothermal cooling system of an ancient villa in Costozza (Vicenza, Italy). This section extends the knowledge of the Italian architectural heritage and highlights the importance of rediscovering existing bioclimatic technology solutions, still in operation. An animal structure is analysed: the bug of an insect. This is a bioclimatic archetype and therefore it can be applied to architecture as a biomimetic technology
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Asfour, Omar S. M. "Ventilation characteristics of buildings incorporating different configurations of curved roofs and wind catchers : (with reference to human thermal comfort)." Thesis, University of Nottingham, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437097.
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Lopes, Igor Moreira. "EVALUATION OF TRANSITIONS FOR TESTING AGRICULTURAL VENTILATION FANS WITH THE FAN ASSESSMENT NUMERATION SYSTEM (FANS)." UKnowledge, 2012. http://uknowledge.uky.edu/bae_etds/8.
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The Fan Assessment Numeration System (FANS) is an improved air velocity traverse method for measuring in situ fan performance. The FANS has been widely used, but variations of its test procedure are commonly employed to accommodate physical or operational barriers encountered in the field. This laboratory study evaluated the use of transitions to connect a 1.37m FANS unit to two smaller fans (1.22m and 0.91m diameter) and one 1.37m diameter fan. Tests were conducted with the FANS unit positioned on both intake and discharge sides of the fans. Three different transition angles (30o, 45o and 60o) and the use of no transition were evaluated. Discharge tests were also performed with no enclosed connection between FANS and fan housings. A different experiment was conducted for each fan size. Data was analyzed by comparing test results to the control with Dunnett’s procedure. Results showed significant differences as much as 5.3% ± 1.20% for intake treatments, 17.2% ± 3.04% for sealed discharge treatments and 37.1% ± 12.24% for discharge treatments with no enclosed connection. All transition angles produced similar fan test results. Differences between test results from the discharge and control treatments increased as differences between FANS and fan dimensions increased.
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Choinière, Yves. "Wind induced natural ventilation of low-rise buildings for livestock housing by the pressure difference method and concentration decay method." Thesis, University of Ottawa (Canada), 1991. http://hdl.handle.net/10393/7702.
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Measurements of the external pressure coefficients around open and sealed 1:20 scale models of a low-rise, naturally ventilated building with a gable roof for livestock housing were made in the NRCC wind tunnel. In addition, the internal pressure coefficients were recorded within the open models. All structural configuration changes of the building had an effect on: the external pressure coefficient distributions, calculated and measured internal pressure coefficients, air inlet and outlet zones, magnitude of the local airflows through individual openings, and on the calculated ventilation rate coefficients. As well, there were considerable differences between results for the sealed and open models especially at the ridge level. Generally, the comparisons between the ventilation rate coefficients of the open and sealed model suggest that the larger the total sidewall, end wall and ridge opening areas were, the greater the discrepancies were between open and sealed models' predictions. (Abstract shortened by UMI.)
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Yifan, Wang, and Huang Yizhang. "Urban Wind and Thermal Environment Simulation - A Case Study of Gävle, Sweden." Thesis, Högskolan i Gävle, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-16605.
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As urbanization and industrialization progressed during the last decades, Urban Heat Island (UHI) has become a major environmental issue to many cities around the world. The effect of UHI differs from area to area due to varying urban scale, population density, construction of urban surface layer, the level of industrialization and type of climate. Researchers have made great efforts in investigating various approaches to Urban Heat Island studies. Monitoring technologies have been widely used in this field, especially Geographic Information System (GIS) and remote sensing technology. Computational Fluid Dynamics (CFD) simulations are also actively applied in wind engineering, which can provide details of air flow over urban areas. The combined application of these technologies can provide the monitoring and simulation of urban wind corridor and thermal environment that can produce relevant information at a lesser time.A research using GIS, remote sensing technology and CFD simulation was done in this project to obtain a holistic view of the urban thermal environment and wind flow for Gävle City. With GIS and remote sensing the thermal image of the city was presented. The temperature data, which were collected from MODIS satellite were transferred and processed by ArcGIS and Global Mapper. The wind flow above the city was simulated through constructing geometric and mathematical model with OpenFOAM. The outcomes of the modeling and simulation identified that the temperature in the city center could possibly reach 35℃ during summers, which can cause the Urban Heat Island to form. Ventilation was also poorer in the city centre, and neither the river nor the green area in the southwest could help ventilate the city. The study result also suggested that certain sites in the city had relatively high wind flow for urban wind turbines to work.This study had used method of Urban Heat Island study with remote sensing and CFD technologies. The model produced from simulation could also be used to further study Gävle city's thermal and wind environment to produce more accurate results.
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Nunes, Daniel Alexandre. "Estudo da ventilação natural por efeito do vento em pavilhões industriais utilizando modelos reduzidos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2006. http://hdl.handle.net/10183/12548.
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A ventilação natural pode ser promovida por dois mecanismos: o denominado efeito chaminé e o efeito dos ventos, porém também podem ocorrer os dois mecanismos simultaneamente. A determinação das vazões de ventilação por efeito do vento, em pavilhões industriais, pode ser realizada a partir de ensaios de modelos reduzidos em túnel de vento, com medição das velocidades do escoamento nas aberturas, ou então, com medição dos coeficientes de pressão em modelos fechados, nas faces onde estão localizadas as aberturas. A metodologia com medição dos coeficientes de pressão, que exige o emprego de um modelo teórico para calcular as vazões, é a forma convencional de usar o túnel de vento como ferramenta no projeto de ventilação. O objetivo deste trabalho é avaliar os procedimentos citados, para calcular as vazões de ventilação por efeito do vento em pavilhões industriais. Para atingir esse objetivo foram ensaiados em túnel de vento dois modelos reduzidos (escala geométrica 1:200) de um pavilhão industrial: um sem aberturas, para a medição dos coeficientes de pressão, e outro, com aberturas de ventilação de área variável, para a medição das velocidades do vento com anemômetro de fio quente. Além da comparação das duas metodologias para determinação das vazões de ventilação, os resultados dos ensaios foram também utilizados para analisar as alterações nas vazões de ventilação e nas velocidades do escoamento do ar decorrentes do fechamento de algumas aberturas do modelo estudado. Conclui-se que as aberturas localizadas na cumeeira e o tipo de escoamento exercem grande influência nas vazões de ventilação. A utilização da metodologia de medição direta de velocidades através de anemômetro de fio quente permite a obtenção de vazões de ventilação sem iterações, com resultados compatíveis com os modelos teóricos que se baseiam na diferença de pressões externas e internas.Natural ventilation in industrial buildings may be promoted by two mechanisms: one due to wind effects and other called chimney effect. However, the two mechanisms may also occur simultaneously. The determination of wind induced ventilation flows in industrial buildings may be performed through wind tunnel tests, with measurement of discharge velocity at openings, or else, with measurement of the pressure coefficients at the face of the buildings, where the openings are located. The methodology which employs the pressure coefficients requires the use of a theoretical model to calculate the flows, being the conventional way of using the wind tunnel as a tool in the ventilation project. The objective of this work is to evaluate the experimental procedures previously mentioned in order to be able to calculate the wind induced ventilation flows in industrial buildings. To reach this objective, two reduced models of an industrial building were tested at a geometric scale 1:200; one without openings, for the measurement of the pressure coefficients, and the other with ventilation openings with variable area, for the measurement of the wind velocities by the use of hot-wire anemometer. Different opening combinations were also tested and the flows analyzed. It is concluded that the opening types and the different flows exert a big influence in the ventilation flows and, therefore, in the natural ventilation itself. Also, the direct velocity measurement technique, through hot-wire anemometer, allows the ventilation flows to obtained directly, without interactions, being the results compatible with the theoretical models based on pressure differences.
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Kalua, Amos. "Framework for Integrated Multi-Scale CFD Simulations in Architectural Design." Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/105013.
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An important aspect in the process of architectural design is the testing of solution alternatives in order to evaluate them on their appropriateness within the context of the design problem. Computational Fluid Dynamics (CFD) analysis is one of the approaches that have gained popularity in the testing of architectural design solutions especially for purposes of evaluating the performance of natural ventilation strategies in buildings. Natural ventilation strategies can reduce the energy consumption in buildings while ensuring the good health and wellbeing of the occupants. In order for natural ventilation strategies to perform as intended, a number of factors interact and these factors must be carefully analysed. CFD simulations provide an affordable platform for such analyses to be undertaken. Traditionally, these simulations have largely followed the direction of Best Practice Guidelines (BPGs) for quality control. These guidelines are built around certain simplifications due to the high computational cost of CFD modelling. However, while the computational cost has increasingly fallen and is predicted to continue to drop, the BPGs have largely remained without significant updates. The need to develop a CFD simulation framework that leverages the contemporary and anticipates the future computational cost and capacity can, therefore, not be overemphasised. When conducting CFD simulations during the process of architectural design, the variability of the wind flow field including the wind direction and its velocity constitute an important input parameter. Presently, however, in many simulations, the wind direction is largely used in a steady state manner. It is assumed that the direction of flow downwind of a meteorological station remains constant. This assumption may potentially compromise the integrity of CFD modelling as in reality, the wind flow field is bound to be dynamic from place to place. In order to improve the accuracy of the CFD simulations for architectural design, it is therefore necessary to adequately account for this variability. This study was a two-pronged investigation with the ultimate objective of improving the accuracy of the CFD simulations that are used in the architectural design process, particularly for the design and analysis of natural ventilation strategies. Firstly, a framework for integrated meso-scale and building scale CFD simulations was developed. Secondly, the newly developed framework was then implemented by deploying it to study the variability of the wind flow field between a reference meteorological station, the Virginia Tech Airport, and a selected localized building scale site on the Virginia Tech campus. The findings confirmed that the wind flow field varies from place to place and showed that the newly developed framework was able to capture this variation, ultimately, generating a wind flow field characterization representative of the conditions prevalent at the localized building site. This framework can be particularly useful when undertaking de-coupled CFD simulations to design and analyse natural ventilation strategies in the building design process.Doctor of Philosophy
The use of natural ventilation strategies in building design has been identified as one viable pathway toward minimizing energy consumption in buildings. Natural ventilation can also reduce the prevalence of the Sick Building Syndrome (SBS) and enhance the productivity of building occupants. This research study sought to develop a framework that can improve the usage of Computational Fluid Dynamics (CFD) analyses in the architectural design process for purposes of enhancing the efficiency of natural ventilation strategies in buildings. CFD is a branch of computational physics that studies the behaviour of fluids as they move from one point to another. The usage of CFD analyses in architectural design requires the input of wind environment data such as direction and velocity. Presently, this data is obtained from a weather station and there is an assumption that this data remains the same even for a building site located at a considerable distance away from the weather station. This potentially compromises the accuracy of the CFD analyses as studies have shown that due to a number of factors such the urban built form, vegetation, terrain and others, the wind environment is bound to vary from one point to another. This study sought to develop a framework that quantifies this variation and provides a way for translating the wind data obtained from a weather station to data that more accurately characterizes a local building site. With this accurate site wind data, the CFD analyses can then provide more meaningful insights into the use of natural ventilation in the process of architectural design. This newly developed framework was deployed on a study site at Virginia Tech. The findings showed that the framework was able to demonstrate that the wind flow field varies from one place to another and it also provided a way to capture this variation, ultimately, generating a wind flow field characterization that was more representative of the local conditions.
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Tecle, Amanuel Sebhatu. "Evaluation of Wind-Induced Internal Pressure In Low-Rise Buildings: A Multi Scale Experimental and Numerical Approach." FIU Digital Commons, 2011. http://digitalcommons.fiu.edu/etd/529.
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Hurricane is one of the most destructive and costly natural hazard to the built environment and its impact on low-rise buildings, particularity, is beyond acceptable. The major objective of this research was to perform a parametric evaluation of internal pressure (IP) for wind-resistant design of low-rise buildings and wind-driven natural ventilation applications. For this purpose, a multi-scale experimental, i.e. full-scale at Wall of Wind (WoW) and small-scale at Boundary Layer Wind Tunnel (BLWT), and a Computational Fluid Dynamics (CFD) approach was adopted. This provided new capability to assess wind pressures realistically on internal volumes ranging from small spaces formed between roof tiles and its deck to attic to room partitions. Effects of sudden breaching, existing dominant openings on building envelopes as well as compartmentalization of building interior on the IP were systematically investigated.
Results of this research indicated: (i) for sudden breaching of dominant openings, the transient overshooting response was lower than the subsequent steady state peak IP and internal volume correction for low-wind-speed testing facilities was necessary. For example a building without volume correction experienced a response four times faster and exhibited 30-40% lower mean and peak IP; (ii) for existing openings, vent openings uniformly distributed along the roof alleviated, whereas one sided openings aggravated the IP; (iii) larger dominant openings exhibited a higher IP on the building envelope, and an off-center opening on the wall exhibited (30-40%) higher IP than center located openings; (iv) compartmentalization amplified the intensity of IP and; (v) significant underneath pressure was measured for field tiles, warranting its consideration during net pressure evaluations. The study aimed at wind driven natural ventilation indicated: (i) the IP due to cross ventilation was 1.5 to 2.5 times higher for Ainlet/Aoutlet>1 compared to cases where Ainlet/AoutletCFD based IP responses. Comparisons with ASCE 7-10 consistently demonstrated that the code underestimated peak positive and suction IP.
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Castaño, Hector Fabian Marin. "Impacto de dispositivos de sombreamento externos e muro na ventilação natural e no desempenho térmico de uma habitação de interesse social térrea." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/102/102131/tde-04092017-125132/.
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Uma importante estratégia de projeto para melhorar o desempenho térmico das edificações em climas quentes e úmidos é a adoção conjunta da ventilação natural e de dispositivos de sombreamento. Contudo, quando a ventilação natural é ocasionada pela ação dos ventos nas edificações, as pressões do vento nas envoltórias da edificação são alteradas com a presença de elementos externos próximos que mudam as características do fluxo incidente. Deste modo, o presente trabalho tem como objetivo avaliar os impactos na ventilação natural, e nas temperaturas internas do ar e/ou no conforto térmico de uma habitação térrea em um clima quente e úmido, a partir do uso de diferentes dispositivos de sombreamento externos e muro. Para isso, foram realizadas simulações computacionais no programa EnergyPlus através do módulo AirflowNetwork. Foram realizados ensaios em túnel de vento de Camada Limite Atmosférica (CLA) para a obtenção dos coeficientes de pressão (Cps). Os resultados apontaram impactos específicos a cada elemento estudado, no entanto o fenômeno mais frequente nos casos com dispositivos de sombreamento foi a redução dos efeitos de sobrepressão e sucção. Quanto aos seus impactos nas renovações de ar, estes provocaram uma diminuição do fluxo de ar e, consequentemente, o aumento da temperatura no período predominantemente noturno. Entretanto, foi observado um maior impacto na atenuação das temperaturas internas nos períodos diurnos, que prevaleceu sobre o aumento nos períodos de ventilação. Destacou-se, dentre os dispositivos de sombreamento estudados, as proteções tipo veneziana por proporcionarem um melhor desempenho térmico. Já os muros, dentre todos os elementos estudados, foram os que tiveram maior impacto nos Cps. Tal fenômeno significou a diminuição da taxa de renovação de ar dentre 50 e 75%. O impacto mais sobressalente nas temperaturas internas nestes casos foi o aumento destas no período noturno, limitando o potencial da ventilação natural para a remoção de calor da edificaçãoAn important design strategy for improving the thermal performance of buildings in hot and humid climates is the adoption of natural ventilation strategies and shading devices combined. However, when natural ventilation is wind-driven, the wind pressures on the building envelope are altered by the presence of nearby external elements that change the incident flows characteristics. Thus, the present work aims to evaluate the impacts on natural ventilation, and the internal air temperatures and/or the thermal comfort of a single ground floor low-cost house in a hot and humid climate, considering the use of different external shading devices and walls. For such, computational simulations were performed in the EnergyPlus program using the AirflowNetwork module. Atmospheric Limit Wind (CLA) wind tunnel tests were performed to obtain pressure coefficients (Cps). The results indicated specific impacts to each element studied, however the most frequent phenomenon in cases with shading devices was the reduction of the effects of overpressure and suction. As for their impacts on air changes rate, they caused a decrease in airflow and, consequently, an increase in temperature predominantly in the nocturnal period. However, a greater impact was observed in the attenuation of internal temperatures in the daytime periods, which prevailed over the increase in ventilation periods., Among the shading devices studied, venetian type protections for providing better thermal performance were highlighted. Among all the elements studied, the walls had the greatest impact on the Cps. This phenomenon meant the reduction of the air changes rate between 50 and 75%. The most significant impact on internal temperatures in these cases was the their increase at night, limiting the potential of natural ventilation to the removal of heat from the building.
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Lukiantchuki, Marieli Azoia. "Sheds extratores e captadores de ar para indução da ventilação natural em edificações." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/102/102131/tde-07082015-180544/.
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A ventilação natural é uma das estratégias mais eficientes para o condicionamento térmico passivo de edificações, ocorrendo por ação dos ventos, por efeito chaminé ou pela combinação de ambos. Em áreas densamente ocupadas, a velocidade do vento é reduzida pelos diversos obstáculos locais, tornando o efeito chaminé e a captação pela cobertura as alternativas mais viáveis para indução da ventilação natural em edificações. Dentre as estratégias de ventilação, destacam-se os sheds, aberturas no telhado, que funcionam como captadores ou extratores de ar, dependendo de sua localização em relação aos ventos dominantes. Apesar de terem um grande potencial, são pouco utilizados devido à falta de dados técnicos acessíveis ao projetista. Além disso, muitas vezes são utilizados para captação ou para extração do ar de forma aleatória, sem uma análise da influência dos parâmetros projetuais na ventilação natural. Essa pesquisa parte da hipótese que existe diferença nesses parâmetros para um shed extrator e para um shed captador de ar e que é possível otimizar a ventilação natural através desses dispositivos. O objetivo geral foi avaliar o impacto de diferentes parâmetros projetuais e climáticos no desempenho de sheds captadores e extratores de ar e propor diretrizes para o projeto desses dispositivos. A metodologia foi composta de estudos paramétricos, a fim de investigar a interdependência de diferentes parâmetros projetuais na ventilação natural por sheds e realizar análises comparativas. O processo baseou-se em análises numéricas através de simulações CFD e a verificação desses resultados por meio de ensaios experimentais em túnel de vento. As análises mostraram uma boa compatibilidade entre os resultados numéricos e experimentais, obtendo uma diferença de no máximo 10% entre as duas ferramentas para a maioria dos pontos monitorados. Com relação às simulações computacionais, constatou-se que o desempenho de sheds é fortemente influenciado pela velocidade e pelos ângulos de incidência dos ventos externos. Além disso, notou-se que existem diferenças nos parâmetros projetuais para um shed extrator e para um captador, sendo que alguns casos apresentaram bons desempenhos em ambas as situações. Por fim, conclui-se que é possível otimizar o uso da ventilação natural através desses dispositivos, sendo que esses resultados auxiliam a prática do projeto arquitetônico na determinação de configurações adequadas.Natural ventilation is one of the most important strategies for passive cooling of indoor environments. It can occur by wind forces, stack effect or a combination of both strategies. In urban areas the wind speed is reduced due to several obstacles. Stack effect and air intake by the roof can be viable alternatives to induce natural ventilation in buildings. Among the ventilation strategies, sheds can be highlighted. These structures consist of roof openings that work as collectors or extractors of air, depending on their location in relation to the prevailing wind directions. Although they have great potential, they are seldom used by Brazilian architecture, due to lack of technical data available to the designer. Besides, sometimes the sheds are used for air intake or exhaustion without any detailed analysis on the influence of different building design parameters on natural ventilation. The starting hypothesis of this research is that there is a difference in construction parameters for an exhaustion and intake sheds and it is possible to optimize the use of natural ventilation through these devices. The research aims to investigate the potential of air extracting and capturing sheds to promote indoor natural ventilation and proposes guidelines for the design of these devices. The applied methodology consists on parametric studies to investigate the interdependence of different design parameters for natural ventilation in sheds and perform comparative analyzes. The procedure was based on CFD simulations and the verification of such results through experimental tests using wind tunnel. The analyses showed a good compatibility between the numerical and experimental results, obtaining a maximum difference of 10% between the two tools for most of the monitored points. The computer simulations showed that sheds performance is strongly influenced by the external wind speed and its incidence angles. In addition, it was noted that there are differences in design parameters for air extracting and capturing sheds and some cases showed a good performance in both situations. Finally, it was concluded that it is possible to optimize the use of natural ventilation through these devices, and these results support the practice of architectural design in determining appropriate settings.
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Queiroga, Silvana Chaves Claudino de. "Estudo em túnel de vento da relação entre o padrão de adensamento e o conforto de pedestres : aplicação à região do Altiplano Cabo Branco, João Pessoa-PB." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/180140.
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O padrão de adensamento urbano impacta no conforto do pedestre no que diz respeito, sobretudo, à possibilidade de alterar as condições de vento ao nível do solo gerando zonas de desconforto. As cidades convivem com constantes mudanças em sua configuração tanto pelo adensamento quanto pela verticalização de suas estruturas, esta condição modifica a ventilação natural urbana, alterando as condições de vento no entorno de edifícios, o que afeta o escoamento de ar ao nível do solo, atingindo o conforto do pedestre. Então, o objetivo desta pesquisa é analisar o conforto do pedestre em relação ao vento em analogia a padrões de adensamento urbanos, considerando ensaios experimentais em túnel de vento a partir da aplicação em área urbana da cidade de João Pessoa-PB. A área investigada é parte dos bairros Altiplano Cabo Branco e Cabo Branco, localidade que, nos últimos anos, tem passado por grandes mudanças em sua configuração, respaldadas por alterações do instrumento urbanístico. Motivando o estudo de padrão de ocupação e seu reflexo no conforto do pedestre frente ao vento, pelo meio da avaliação de duas configurações de vizinhança ensaiadas em túnel de vento. As proposições referem-se a padrão de adensamento antigo, anterior ao ano de 2005 e adensamento recente, referente a situação atual, ano de 2012, as duas situações propostas reproduzem circunstâncias reais Os experimentos foram realizados com modelos, M1 e M2, em escala reduzida, referente a 1/400; no Túnel de Vento Prof. Joaquim Blessmann da Universidade Federal do Rio Grande do Sul, mesa M-II; pela simulação de vento do tipo turbulento, compatível com as condições do local estudado. Consideraram-se as configurações de ensaio utilizadas nesse túnel de vento para simular perfis de velocidade média, que correspondem às categorias de terreno definidos na NBR 6.123/1988, vento mar, categoria I, e vento terra, entre a categoria III e IV. Iniciou-se com os ensaios de escoamento de camada limite, que envolve a aquisição de dados de velocidades instantâneas do vento, obtidos com anemômetros de fio quente, a partir de malha de medição definida, sendo, sete linhas, oito posições e dez alturas, para dois rumos de vento, sendo 900 e 1500, definindo o comportamento do vento para a área E, prosseguiram-se com os ensaios de conforto do pedestre, através de medições de velocidades ao nível do solo para trinta e seis posições, pontos distribuídos por passeios e calçadas, por meio de sondas de pedestres, sondas tipo Irwin, realizando tomadas para vinte e quatro ângulos de incidência de vento, marcados a cada 150. Para aferir as condições de vento para o pedestre, utilizaram-se critérios de conforto baseados na Escala Beaufort, que relacionam a atividade, o local e o nível de conforto relativo, pondera ainda acerca de critérios de aceitação para períodos de retorno, um ano, um mês e uma semana. Os resultados obtidos para as configurações de vizinhança referentes ao escoamento para a área e ao conforto do pedestre, foram confrontados, atentando-se que o adensamento urbano modifica consideravelmente o campo de vento de áreas urbanas, atingindo o conforto do pedestre, impossibilitando-o, para algumas posições estudadas, de realizar atividades corriqueiras com conforto. Então, assentam-se fundamentos que orientam a ocupação do solo com vistas à garantia de realização pelo pedestre, com nível de conforto relativo “aceitável”, das atividades inerentes aos usos propostos para o ambiente urbano, colaborando com o planejamento, o controle e a intervenção em áreas urbanizadas, favorecendo, também, o crescimento saudável das cidades.The pattern of urban densification impacts on pedestrian comfort, specially, in relation with the possibility of changing the wind conditions at ground level, generating discomfort zones. Cities live with constant changes in its configuration due to the densification and to the verticalization of its structures. This condition modifies the urban natural ventilation, changing, the wind conditions in the building surroundings, which affects the air outflow at ground level, impacting on pedestrian comfort. The objective of this work is to analyze the relation between the pedestrian comfort and the wind, similarly to the patterns of urban densification, considering experimental tests in wind tunnel, since application in the urban area of João Pessoa-PB city. The investigated area is part of the neighborhoods of Altiplano Cabo Branco and Cabo Branco, João Pessoa-PB, region that, in the last years, has been passing through considerable changings in its configuration, supported by alterations in the urban instrument. Motivating the study of the occupation patterns and its reflection in the pedestrian comfort facing the wind through the analysis of two neighborhood configurations, simulated in the wind tunnel, through experiments. The propositions refer to an old densification before the year of 2005 and to a recent densification, referring to a current situation, both proposed situations reproduce real circumstances The experiments were realized with models, M1 and M2, in reduced scale, regarding 1/400; in the Túnel de Vento Prof. Joaquim Blessmann from Universidade Federal do Rio Grande do Sul, table M-II; by the simulation of the turbulent wind, compatible with the conditions of the studied place. The configurations of assay used in this wind tunnel to simulate average velocity profiles were considered, which correspond to the ground defined in NBR 6.123/1988, sea wind, category I, and land wind, between the category III and IV. Beginning with experiments of the boundary layer’s outflow that are related to the acquisition of the wind’s instantaneous velocities’ data obtained with hot wire anemometers, from the defined measurements mesh, being seven lines, eight positions and ten heights, to two wind courses, being 900 and 1500, defining the behavior of the wind to the area. And, continued with the assays of pedestrian comfort, through measurements of the velocities at ground level for thirty six positions, points distributed for sidewalks, through pedestrian sensors, sensors of the Irwin type, realizing measurements for twenty four incidence angles, marked every 150 In order to verify the wind conditions for the pedestrians, comfort criterions based in the Escala Beaufort were utilized, which make a relation of the activity, the place and the relative comfort level, it still ponders about the acceptance criterions for return periods, one year, one month and one week. The results obtained for the configurations of the neighborhoods referents to the area’s outflow and to the pedestrian comfort were confronted, paying special attention to the fact that the urban densification modifies substantially the wind field of the urban areas, affecting the pedestrian comfort, impossibilitating it, for some studied positions, for realizing everyday activities with comfort. Then, fundamentals that guide the pattern of ground occupation were consolidated, aiming the guaranty of realization by pedestrian, with an “acceptable” relative comfort level, for the activities inherent to the uses proposed to the urban ambient, collaborating with the planning, the control and the intervention in urbanized areas, still assisting the healthy growth of the cities.
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Cóstola, Daniel. "Ventilação por ação do vento no edifício: procedimentos para quantificação." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/16/16132/tde-26102010-144530/.
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Este trabalho tem por objetivo formular um procedimento para a quantificação da vazão do ar promovida pela ação do vento no interior do edifício, em climas quentes. O procedimento é dividido em cinco partes: obtenção dos dados de vento, transposição dos dados de vento da estação meteorológica para a área de interesse, determinação dos coeficientes de pressão no edifício, determinação dos coeficientes de descarga das aberturas, e o cálculo da vazão no interior do edifício. Diversas ferramentas são apresentadas para a execução de cada etapa, e seu uso e parâmetros de entrada são discutidos. O uso de túnel de vento e a simulação com ferramentas de dinâmica dos fluidos computacional são apresentados em detalhes. O trabalho conclui que estão disponíveis aos projetistas um amplo conjunto de ferramentas para a predição da ventilação natural no interior do edifício, e que somente pelo seu uso criterioso, as conclusões são passiveis de uso no projeto arquitetônico.The aim of this dissertation is to produce a procedure for wind-driven natural ventilation prediction, in hot climate building. The procedure is organized in five parts: wind data obtaining, topographic e roughness correction, pressure coefficient determination, discharge coefficient determination, and flow rate calculation inside the building. The dissertation presents some tools to execute each part of the procedure, and the specificities of those tools are discussed. Wind tunnel experiment and computation fluid dynamic simulation are presented in detail. The research conclusion is that designers have many tools avaliable to performe a natural ventilation prediction, but just concient use will produce reliable results for architectural design.
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Andrade, Nixon Cesar de 1976. "Estudo da ventilação natural em edificações com captadores de vento multidirecionais por meio de ensaios em túnel de vento e simulações computacionais." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258056.
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Orientador: Lucila Chebel LabakiTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: A ventilação natural é uma das estratégias mais adequadas para o resfriamento passivo dos edifícios e para a manutenção da qualidade do ar. Uma das alternativas existentes para se alcançar tal proposição é a utilização de torres de vento situadas acima do nível da cobertura, as quais podem funcionar como captadores ou extratores de ar. Esta pesquisa tem como objetivo geral avaliar quatro tipos de torres, atuando como captadores: a unidirecional, com uma abertura para a entrada de vento, em locais onde o vento se movimenta predominantemente em uma direção; a tetradirecional, com quatro aberturas; a octodirecional, com oito aberturas e a dodecadirecional, com doze aberturas; em locais em que o vento age em várias direções. Para alcançar o objetivo utilizaram-se ensaios em túnel de vento e simulações no software CFX®, os quais permitiram estudar as características técnicas das torres analisadas e seus efeitos sobre a ventilação interna do ambiente, bem como contribuir para a difusão desse sistema de ventilação no Brasil. O desenvolvimento do trabalho foi dividido nas seguintes etapas: definição das geometrias das torres; definição, construção e instrumentação das maquetes; definição dos ângulos de incidência do vento; ensaios no túnel de vento e simulações no software CFX®: velocidade e pressão. Os resultados obtidos a partir de uma série de experimentos e simulações computacionais permitiram a análise e comparação dos diversos projetos propostos, auxiliando, portanto, na determinação das configurações mais adequadas, além da verificação da compatibilidade entre os dois tipos de estudo, concluindo que as torres octodirecional e dodecadirecional são as mais eficientes, pois proporcionam maiores valores de velocidade do ar interno na maioria das posições consideradas. Desta forma, utilizando o túnel de vento e o CFX®, as análises possibilitaram desenvolver melhorias para os ambientes avaliados, no que se refere ao desempenho da ventilação. Isso proporcionará melhores taxas de conforto aos usuários da edificação, considerando todas as aberturas para permitir o fluxo do vento em qualquer situação. Ademais, podem-se verificar as distribuições das aberturas de entrada e saída mais adequadas para captação e distribuição do vento no interior dos ambientes, proporcionando melhores condições de conforto térmico
Abstract: Natural ventilation is one of the most appropriate strategies for passive cooling of buildings and the maintenance of air quality. One of the alternatives for achieving such proposal is the use of wind towers above the level of the roof, which can function as air catchers or extractors. This research aims to evaluate four types of towers, acting as air catchers: unidirectional, with an opening for the entrance of the wind, in locations where the wind moves predominantly in one direction, the tetradirectional, with four openings, the octodirectional, with eight openings and dodecadirectional, with twelve openings, in locations where the wind moves in various directions. To achieve the goal, tests in wind tunnel and simulations in CFX® software were performed, which allowed the study of the technical characteristics of the analyzed towers and their effects on the indoors ventilation, as well as the contribution to the spread of this ventilation system in Brazil. The methodology was divided into the following steps: the definition of the geometry of the towers; definition, construction and instrumentation of the models; definition of the angles of the incidence of the wind; wind tunnel tests and simulations in CFX® software: speed and pressure. The obtained results from a series of experimental and computational simulations allowed the analysis and comparison of the various proposed design configurations, helping, therefore, in determining the most appropriate settings, besides the verification of compatibility between the two types of study, concluding that the octodirectional and dodecadirectional towers are the most efficient ones , as they provide higher rate of indoor air speed in most considered positions. Thus, using the wind tunnel and CFX®, the analysis allowed the development of enhancements to the analyzed environments, concerning the performance of the ventilation. This will provide better comfort rates to the users of the building, considering all openings to allow the wind flow in any situation. Furthermore, the most suitable distribution of inlet and outlet openings for the catchment and distribution of the wind within the environments may be verified, providing better conditions of thermal comfort
Doutorado
Arquitetura e Construção
Doutor em Engenharia Civil
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Hayati, Abolfazl. "Natural Ventilation and Air Infiltration in Large Single‑Zone Buildings : Measurements and Modelling with Reference to Historical Churches." Doctoral thesis, Högskolan i Gävle, Energisystem, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-24612.
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Natural ventilation is the dominating ventilation process in ancient buildings like churches, and also in most domestic buildings in Sweden and in the rest of the world. These buildings are naturally ventilated via air infiltration and airing. Air infiltration is the airflow through adventitious leakages in the building envelope, while airing is the intentional air exchange through large openings like windows and doors. Airing can in turn be performed either as single-sided (one opening) or as cross flow ventilation (two or more openings located on different walls). The total air exchange affects heating energy and indoor air quality. In churches, deposition of airborne particles causes gradual soiling of indoor surfaces, including paintings and other pieces of art. Significant amounts of particles are emitted from visitors and from candles, incense, etc. Temporary airing is likely to reduce this problem, and it can also be used to adjust the indoor temperature. The present study investigates mechanisms and prediction models regarding air infiltration and open-door airing by means of field measurements, experiments in wind tunnel and computer modelling. In natural ventilation, both air infiltration and airing share the same driving forces, i.e. wind and buoyancy (indoor-outdoor temperature differences). Both forces turn out to be difficult to predict, especially wind induced flows and the combination of buoyancy and wind. In the first part of the present study, two of the most established models for predicting air infiltration rate in buildings were evaluated against measurements in three historical stone churches in Sweden. A correction factor of 0.8 is introduced to adjust one of the studied models (which yielded better predictions) for fitting the large single zones like churches. Based on field investigation and IR-thermography inspections, a detailed numerical model was developed for prediction of air infiltration, where input data included assessed level of the neutral pressure level (NPL). The model functionality was validated against measurements in one of the case studies, indicating reasonable prediction capability. It is suggested that this model is further developed by including a more systematic calibration system for more building types and with different weather conditions. Regarding airing, both single-sided and cross flow rates through the porches of various church buildings were measured with tracer gas method, as well as through direct measurements of the air velocity in a porch opening. Measurement results were compared with predictions attained from four previously developed models for single‑sided ventilation. Models that include terms for wind turbulence were found to yield somewhat better predictions. According to the performed measurements, the magnitude of one hour single-sided open-door airing in a church typically yields around 50% air exchange, indicating that this is a workable ventilation method, also for such large building volumes. A practical kind of diagram to facilitate estimation of suitable airing period is presented. The ability of the IDA Indoor Climate and Energy (IDA-ICE) computer program to predict airing rates was examined by comparing with field measurements in a church. The programs’ predictions of single-sided airflows through an open door of the church were of the same magnitude as the measured ones; however, the effect of wind direction was not well captured by the program, indicating a development potential. Finally, wind driven air flows through porch type openings of a church model were studied in a wind tunnel, where the airing rates were measured by tracer gas. At single-sided airing, a higher flow rate was observed at higher wind turbulence and when the opening was on the windward side of the building, in agreement with field measurements. Further, the airing rate was on the order of 15 times higher at cross flow than at single-sided airing. Realization of cross flow thus seems highly recommendable for enhanced airing. Calibration constants for a simple equation for wind driven flow through porches are presented. The measurements also indicate that advection through turbulence is a more important airing mechanism than pumping. The present work adds knowledge particularly to the issues of air infiltration and airing through doors, in large single zones. The results can be applicable also to other kinds of large single-zone buildings, like industry halls, atriums and sports halls.Naturlig ventilation är den dominerande ventilationsprocessen i äldre byggnader såsom kyrkor, och även i de flesta småhus i Sverige och övriga delar av världen. Luftinfiltration och vädring utgör viktiga komponenter i naturlig ventilation, där luftinfiltration är luftflöde genom oavsiktliga läckage i byggnadsskalet, medan vädring är avsiktligt luftutbyte genom stora öppningar såsom fönster och dörrar/portar. Vädring kan i sin tur ske ensidigt (genom en öppning) eller som tvärdrag (genom två eller flera öppningar belägna på olika ytterväggar). Det totala luftutbytet påverkar värmeförluster och inomhusluftens kvalité. I kyrkor orsakar avsättning av luftpartiklar en gradvis nedsmutsning av invändiga ytor, inklusive väggmålningar och andra konstföremål. Betydande mängder partiklar avges från besökare, tända ljus, rökelse, o.d. Tillfällig vädring kan minska detta problem, men även användas för att justera innetemperaturen. Föreliggande studie analyserar mekanismer och predikteringsmodeller gällande luftinfiltration och dörrvädring genom fältmätningar, vindtunnelförsök och datorsimuleringar. Luftinfiltration och vädring har samma drivkrafter, d.v.s. vind och termik (inne‑ute temperaturskillnader). Båda dessa drivkrafter är svåra att predicera, särskilt vindinducerade flöden och kombinationen av termik och vind. Två av de mest etablerade modellerna för luftinfiltrationsprediktering i byggnader har utvärderats via mätningar i tre kulturhistoriska stenkyrkor i Sverige. En korrigeringsfaktor av 0,8 föreslås för bättre prediktion av den ena modellen (som gav bäst resultat) gällande höga en-zonsbyggnader såsom kyrkor. En detaljerad numerisk modell är utvecklad för luftinfiltrationsprediktering, där indata baseras på fältundersökningar, inkl. IR-termografering och uppmätt av neutrala tryckplanet (NPL). Modellens funktionalitet har validerats via mätningar i en av fallstudierna och pekar på tämligen god prediktionsprestanda. Vidare utveckling av modellen föreslås, inkl. ett mer systematiskt kalibreringssystem, för olika typer av byggnader och väderförhållanden. Gällande vädring mättes både ensidigt flöde och tvärdrag genom portar i olika kyrkobyggnader med hjälp av spårgas samt direkta lufthastighetsmätningar i portöppning. Mätresultaten jämfördes med erhållna prediktioner från fyra tidigare utvecklade modeller för ensidig ventilation. De modeller som tog hänsyn till vindturbulens gav något bättre resultat. Enligt utförda mätningar medför en timmes ensidig portvädring i en kyrka cirka 50 % luftutbyte, vilket indikerar att detta är en tillämpbar ventilationsmetod, även för så pass stora byggnadsvolymer. Ett särskilt vädringsdiagram presenteras, som syftar till att underlätta uppskattning av erforderlig vädringsperiod. Vidare studerades predikteringsprestanda hos IDA Indoor Climate and Energy (IDA-ICE) simuleringsprogram avseende vädring, där simuleringsdata jämfördes med fältmätningar i en kyrka. Programmets prediktion av ensidigt luftflöde genom en öppen kyrkport var av samma storlekordning som det uppmäta; dock klarade programmet inte av att hantera inverkan av vindriktning så väl, vilket pekar på en utvecklingspotential. Avslutningsvis undersöktes vinddrivet flöde igenom portöppningar i en kyrkmodell i vindtunnel, där luftomsättningen mättes med hjälp av spårgasmetoden. Vid ensidig vädring observerades högre flöde vid högre vindturbulens och när öppningen var på vindsidan av byggnaden, i överensstämmelse med fältmätningarna. Dessutom var vädringsflödet vid tvärdrag i storleksordningen 15 högre än det vid ensidig vädring. Det verkar alltså som att man kan öka vädringstakten avsevärt om man kan åstadkomma tvärdrag. Kalibreringskonstanter presenteras också för en enkel ekvation för vinddrivet flöde genom portar. Vindtunnelstudien indikerar vidare att advektion genom turbulens är en viktigare vädringsmekanism än pumpning. Föreliggande arbete bidrar med kunskap speciellt kring luftinfiltration och vädring genom portar i höga en-zonsbyggnader. Resultaten kan även vara tillämpliga på andra typer av höga en-zonsbyggnader såsom industrihallar, atrier/ljusgårdar och idrottshallar.
Church project
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Зарубін, Олександр Олегович. "Термодинамічний аналіз ефективності теплонасосних схем опалення з використанням теплоти повітряних техногенних викидів." Master's thesis, КПІ ім. Ігоря Сікорського, 2021. https://ela.kpi.ua/handle/123456789/41699.
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Магістерська дисертація на тему «Термодинамічний аналіз ефективності теплонасосних схем опалення з використанням теплоти повітряних техногенних викидів»: 92 с., 46 рис., 2 табл., 3додатки, 18 джерел.
Об’єкт дослідження – теплонасосна система опалення з використанням теплоти повітряних техногенних викидів теплоти.
Мета роботи – розрахунок і аналіз оптимальних умов для максимізації енергетичної ефективності роботи теплонасосної схеми низькотемпературного водяного опалення з використанням теплоти повітряних техногенних викидів, враховуючи такі фактори як умови навколишнього середовища та специфіку об’єкту теплопостачання. Наведено результати літературного огляду, в якому було досліджено шляхи вирішення глобальної проблеми енергозбереження шляхом впровадження теплонасосних технологій. Було встановлено, що в якості низькотемпературного вторинного джерела теплоти може бути використано витяжне вентиляційне повітря з підвищеним температурним потенціалом від високотемпературних технологічних установок, який раніше було змарновано.
Представлено теплонасосну схему опалення, що працює за рахунок утилізації теплоти повітряних техногенних викидів. Базуючись на методі балансних рівнянь, було розроблено теоретичну модель теплонасосної системи теплопостачання та методику термодинамічного аналізу ефективності системи з урахуванням характеристик та умов навколишнього середовища. За допомогою числового розрахунку визначено умови досягнення максимального корисного ефекту у системі теплонасосної схеми опалення, отриманого в результаті утилізації теплоти техногенного повітряного джерела, та оптимальний ступінь охолодження теплоносія у випарнику теплового насоса. Наведено та проаналізовано графіки питомого корисного ефекту, отриманого внаслідок утилізації теплоти техногенних повітряних джерел теплоти за допомогою теплового насосу, оптимальної температури вентиляційних викидів на виході із випарника ТН та ступеню використання цих викидів від температури навколишнього середовища, температур гріючого теплоносія в системі опалення і температур техногенних повітряних викидів. Проаналізовано ефективність використання запропонованої системи.
На основі проведених досліджень було підготовлено і подано до публікації статтю в науковому журналі і підготовлено тези доповіді на міжнародну конференцію.Master's thesis on the topic " Thermodynamic analysis of the efficiency of heat pump heating schemes using the heat of man-made emissions ": 92 p., 46 fig., 2 tables, 3 annexes, 18 sources. The results of the literature review are presented, in which the ways of solving the global problem of energy saving by introduction of heat pump technologies were investigated. It was found that as a low-temperature secondary heat source can be used exhaust ventilation air with high temperature potential from high-temperature technological installations, which was previously wasted. The heat pump scheme of heating working at the expense of utilization of heat of air technogenic emissions is presented. Based on the method of balance equations, a theoretical model of the heat pump heat supply system and a method of thermodynamic analysis of the system efficiency taking into account the characteristics and environmental conditions were developed. Using numerical calculation, the conditions for achieving the maximum useful effect in the system of the heat pump heating scheme, obtained as a result of heat utilization of a man-made air source, and the optimal degree of cooling of the coolant in the heat pump evaporator are determined. Graphs of specific effect obtained due to heat utilization of man-made air heat sources by means of heat pump, optimal temperature of ventilation emissions at the outlet of the HP evaporator and the degree of use of these emissions from ambient temperature, temperatures of heating coolant in heating system and man-made air temperature. The efficiency of using the proposed system is analyzed.
Магистерская диссертация на тему «Термодинамический анализ эффективности теплонасосных схем отопления с использованием теплоты воздушных техногенных выбросов»: 92 с., 46 рис., 2 табл., 3 приложения, 18 источников. Приведены результаты литературного поиска, в котором были исследованы пути решения глобальной проблемы энергосбережения путем внедрения теплонасосных технологий. Было установлено, что в качестве низкотемпературного вторичного источника теплоты может быть использован вытяжной вентиляционный воздух от высокотемпературных технологических установок с повышенным температурным потенциалом, который ранее был неиспользован. Представлена теплонасосная схема отопления, которая работает за счет утилизации теплоты воздушных техногенных выбросов. Основываясь на методе балансных уравнений, было разработана теоретическая модель теплонасосной системы теплоснабжения и методика термодинамического анализа эффективности системы с учетом характеристик и условий окружающей среды. С помощью численного расчета определены условия достижения максимального положительного эффекта в системе теплонасосной схемы отопления, полученного в результате утилизации теплоты техногенного воздушного источника, и оптимальную степень охлаждения теплоносителя в испарителе теплового насоса. Приведены и проанализированы графики удельного полезного эффекта, полученного в результате утилизации теплоты техногенных воздушных источников теплоты с помощью теплового насоса, оптимальной температуры вентиляционных выбросов на выходе из испарителя ТН и степени использования этих выбросов от температуры окружающей среды, температур греющего теплоносителя в системе отопления и температур техногенных воздушных выбросов. Проанализирована эффективность использования предложенной системы. На основе проведенных исследований была опубликована статья в научном журнале.
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Missenden, J. F. "The influence of delta plan wing vortex generators upon room air movement." Thesis, London South Bank University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377694.
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Sanchez, Marc. "Etude des extracteurs d'air hybrides éoliens : conception de géométries et analyse des écoulements." Thesis, Perpignan, 2015. http://www.theses.fr/2015PERP0040/document.
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Ce travail de thèse concerne l'étude d'extracteurs d'air hybrides éoliens. Il se décompose en des investigations amont et appliquées. Dans la partie amont, des simulations fines ont été effectuées en conduite carrée avec et sans rotation, pour des nombres de Reynolds turbulents de l'ordre de 600, afin d'analyser l'impact de la rotation sur la turbulence. Elles ont montré que la rotation rompt la symétrie de l'écoulement. La partie appliquée est dédiée à la conception d'une nouvelle géométrie d'extracteur d'air. Cette géométrie a été proposée à partir de l'analyse de simulations RANS. Ses performances ont été confirmées par des mesures expérimentales sur banc d'essais. Les tests en soufflerie d'un système de captage d'énergie éolienne, conçu pour l'extracteur, ont mis en évidence son adéquation au régime de fonctionnement de l'extracteur. Les essais expérimentaux de l'extracteur complet, montrent que le système de captage apporte une part significative de l'énergie. Des essais en soufflerie ont permis d'observer le comportement global de l'extracteurThis PhD work concerns the study of hybrid air extractors. It is composed of upstream and applied investigations. In the upstream part, fine simulations are realized in square duct flow with and without rotation to analyse the impact of rotation on turbulence. It is found that rotation removes symmetry property of the flow with turbulent Reynolds number of 600. The applied part is dedicated to the conception of a new air extractor geometry. This geometry is proposed from the analyse of RANS simulations. Its performances are confirmed by experimental measurements on test rig. Wind tunnel tests of a wind power capturing system, designed for the extractor, show a good adequation to the operating regime of the extractor. Experimental investigations on the complete air extractor, show the wind power capturing system brings a significant part of the energy. Wind tunnel tests allow to observe the complete air extractor behaviour
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Facchin, Federico. "Pulmonary function evaluation during normal ventilation in both captive and wild bottlenose dolphins (Tursiops truncatus)." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/12643/.
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In this work, pulmonary functions of eight adult bottlenose dolphins (T. truncatus) during normal ventilation have been evaluated (maximal chuff events have not been included). Breath duration, respiratory flow rate, tidal volume and frequency have been measured, data collection involved both male and female dolphins and both captive and wild animals. It came to light that these animals are capable of 5.19 L (maximum recorded 13.11 L) of tidal volume gas exchange during normal ventilation, with an average respiratory frequency of 3.39 breaths*min−1 (range between 2.12-4.65 breaths*min−1, minimum recorded 0,79 breaths*min−1). They are capable of generating great flow too, especially during expiration (23.73±15.41 L*s−1, max recorded 134.14 L*s-1). With this work I provided new data for respiratory physiology of bottlenose dolphin and I looked for differences between wild and captive animals. However, despite the interesting findings obtained, which show a statistical difference between the two groups, I am not going to draw any concrete conclusion, although some differences in tidal volume and flow rate can be related to size and subspecies.
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Prata, Alessandra Rodrigues. "Impacto da altura de edifícios nas condições de ventilação natural do meio urbano." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/16/16131/tde-20012010-113103/.
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Esta pesquisa teve como objetivo verificar a alteração do campo de vento na área de estudo, decorrente da alteração de gabarito quanto à ventilação natural, e avaliar o impacto nas condições de conforto dos pedestres. A verificação das condições de ventilação natural nas cidades, com estudos em modelos, auxilia na elaboração de projetos arquitetônicos, ou de planejamento, possibilitando uma análise da influência do efeito do vento em determinados locais da área em análise. O objeto de estudo da tese é a relação entre a alteração de gabarito (altura dos edifícios) e as mudanças ocasionadas na ventilação natural em espaços urbanos na área entre o Canal 1 e 2 (Bairro Pompéia) na cidade de Santos/SP. Partiu-se da hipótese que a ventilação natural em áreas urbanas depende da altura dos edifícios, da direção e velocidade dos ventos. Foi utilizado método experimental com simulação da configuração urbana em túnel de vento, medidas in loco para a verificação das condições climáticas, simulação com software CFD (Computer Fluids Dynamics) e a aplicação de um índice de neutralidade térmica. Trata-se de uma tese de caráter experimental e exploratório, onde os métodos utilizados demonstraram ser aplicáveis para o entendimento das condições de ventilação natural em meio urbano.The objective of this research is to verify alterations of the wind pattern in the study area, stemming from changes to the grids natural ventilation, and evaluate the impact to the pedestrians comfort conditions. The verification of natural ventilation conditions in cities, with the study of models, aids in the creation of architectural or planning - designs, enabling an analysis of the influence of the effects of wind in certain points of the area in study. This thesis object of study is the relation between changes to the framework (building height) and changes to the natural ventilation in urban environments in the area between Canal 1 and 2 (Bairro Pompéia), in the city of Santos/SP. The hypothesis is that natural ventilation in urban areas depends on the height of buildings, direction and velocity of winds. The study involved an experimental method, with wind-tunnel simulation of the urban grid, in loco measurements of the climate conditions, simulation with CFD software and application of a thermal neutrality index. This thesis is experimental and exploratory in its character, and the methods used proved applicable to the understanding of the natural ventilation conditions in an urban environment.
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Wild, Miriam Olivia [Verfasser]. "Der Effekt von inhalativem Treprostinil im Vergleich zu inhalativem Stickstoffmonoxid auf die Hämodynamik und auf das Ventilations/Perfusions-Verhältnis bei pulmonaler Hypertonie / Miriam Olivia Wild." Gießen : Universitätsbibliothek, 2012. http://d-nb.info/1064173551/34.
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Chen, Yan-Jhih, and 陳彥志. "Wind Tunnel Experiments of Wind-driven Ventilation." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/spc42y.
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碩士國立中央大學
土木工程研究所
96
The wind-driven ventilation for buildings is dependent on the pressure difference between internal and exterior pressure. This study uses theoretical and experimental approaches to investigate wind-driven ventilation. The experiments were carried out in a large scale wind tunnel to study the influences of wind speed, attack angle, size and shape of opening and outdoor flow conditions (steady flow, turbulent flow and gusty flow). Besides, a wind-pressure balance model was developed to calculate the ventilation rate depending on the exterior pressure, opening size and discharge coefficient. The experimental results demonstrate that the wind-pressure balance model can predict ventilation rates of different opening sizes and attack angles in steady flow, but fail to predict the instantaneous ventilation rate in turbulent flow when in the attack angle is 90°. In the gusty flow, the internal pressure has the same fluctuating frequency as the exterior pressure
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Chen, Jhao-Wei, and 陳昭瑋. "Influence of Wind Direction on the Wind-driven Natural Ventilation." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/61489626831155361440.
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碩士國立中央大學
土木工程研究所
99
This study used wind tunnel experiments and tracer gas technique to investigate the influence of wind direction and internal obstacle on the wind-driven ventilation rate of a single-zone building and building with corridor. In addition, external turbulence intensity and the door effect was also examined in this study. The results demonstrate that the maximum ventilation rate occurs at wind direction equals to 45o for building with single-sided opening. It is because the fresh air is easier to enter the building opening when there is an oblique angle between the opening façade and wind direction. This study also found that the ambient turbulence can enhance the shear-induced ventilation rate when the wind direction is parallel to the opening. In addition, the experimental results reveal that the cross-ventilation decreased as the blockage ratio of internal obstacles increased, or the distance between the obstacle and opening decreased. The ventilation rate and resistance factor can be predicted by the resistance model from Chu and Wang (2010). Finally, the results of fan technique display that the discharge coefficient is a function of the door angle, but is independent of the Reynolds number. The concentration variation in the corridor can be predicted by a continuous ventilation model.
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Chiang, Po-fan, and 姜柏帆. "Wind-Driven Cross Ventilation with Internal Obstacles." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/89517477715243939787.
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碩士國立中央大學
土木工程學系
101
Most ventilation models do not consider the influences of furniture and obstacles on building ventilation. This study developed a resistance model to calculate the ventilation rate of wind-driven cross ventilation in a low-rise building with vertical plates in the building. The flow resistances generated by the plates of various sizes were investigated using a Large Eddy Simulation model and wind tunnel experiments. The numerical and experimental results consistently demonstrated that the resistance factor is a function of the internal blockage ratio (ratio of the plate area to the internal cross-section area) and location, but is independent of the external wind speed, building size and opening configuration. It was also found that when the wall porosity is less 3%, the resistances caused by the external openings will dominate the ventilation process and the influence of the internal obstacles on the ventilation rate can be neglected. In addition, it was found that for building without internal obstacle, the resistance caused by the building internal wall should be taken into account when the building length L/H > 2.5. The ventilation rate decreased as the building length increased. Also, the location of external openings can also affect the ventilation process. When the openings on the windward and leeward façades are in the diagonal locations, the ventilation rate is smaller than that of the openings on the center of the façades.
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LAN, TING-WEI, and 藍廷維. "Wind-driven Natural Ventilation of Greenhouses with Vegetation." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/8u6f5f.
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碩士國立中央大學
土木工程學系
105
This study uses wind tunnel experiment and a Large Eddy Simulation (LES) model to investigate the wind-driven ventilation of greenhouses with vegetation inside. The simulation results are validated by wind tunnel experiments. Then the numerical model is used to examine the influences of opening configuration, indoor vegetation on the ventilation rate. The simulation results reveal that the windward pressure was independent of the greenhouse length, while the suction pressure on the leeward side of the single greenhouse is larger than that of multi-span greenhouse. In other words, the pressure difference of single-span greenhouse is larger than that of multi-span greenhouse, and lead to a larger ventilation rate. In addition, multi-span greenhouse has larger internal resistance than that of single-span greenhouse. The ventilation rate can be predicted by a resistance model. The numerical results indicate that the porous drag model is able to predict the velocity distribution inside the greenhouse, and the resistance model can be used to assess the influences of vegetation on the ventilation rate. The results also demonstrate that the ventilation rate is influenced by the inlet and outlet opening areas. Furthermore, the roof opening can substantially increase the ventilation rate in multi-span monoslope greenhouses.
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Chen, Nien-tsu, and 陳念祖. "A Study on Natural Ventilation Efficacy of Wind Deflector." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/06869347225215403311.
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博士國立成功大學
建築學系碩博士班
95
The energy shortage is a major crisis we face today, thus, improving natural ventilation to reduce the energy load caused by the use of air conditioning system is very important. However, the high-density distribution of buildings in urban areas, or the poor design for openings of buildings both have greatly reduced the efficacy of natural ventilation. Also, the indoor air quality in Taiwan has significantly worsened, and the problems of poor ventilation and efficiency are yet to be solved. This study focused on the individual problems for natural ventilation of two modes of a single residential space, which one is with a single-sided opening and the other is with corresponding-sided openings, to probe into the effect of installing horizontal and vertical wind deflectors. The experimental method used CFD numerical method to compute the indoor steady-state air flow, temperature field simulation, and accompanies full-scale experiments results to verify the validity of the simulation, which results were also used as references for simulating boundary conditions. Different external environmental conditions (wind speed or direction) were set in this study, and the Air Change per Hour (ACH), concentration of carbon dioxide, vertical distribution of temperature, and DR (draft rating) for different horizontal wind deflector depths and vertical wind deflector angles were computed. Based on the results, optimal structural scale ranges and usage of wind deflectors were recommended. The results showed that: 1. Installing horizontal deflector at single-sided opening mode For horizontal wind deflector over 9cm can effectively improve the ACH on single-sided ventilation, and the efficiency increases as the wind deflector depth increases. The result is significant when the external wind speed is low (0.3m/s). When the wind deflector depth is 144cm, the ACH (Qnormalize) is the largest, achieving 166~230%, however, DR is very high as well. When the external wind speed is below 2m/s, the wind deflector depth needs to be below 36cm, to meet the DR standard of ASHRAE (DR≦20%) completely. When the wind deflector depth is 4cm, it not only is unable to improve the ACH, but under high wind speed (1~2m/s), ACH would be decreased by 5~13%. Based on the all variables, the optimal wind deflector depth is 18~48cm. 2. Installing vertical wind deflector at corresponding-sided opening mode Under external wind speed of (0.5~2m/s), when the wind direction is parallel to the window, installing vertical wind deflector can averagely improve ACH by 260%. The more efficient wind deflector angle is at 45° (with average increase of 289%), while angle of 67.5° has poorer result (with average increase of 235%). When the wind direction 45° from the building wall, the wind deflector angle of (P＝0°~22.5°) is conducive to an even indoor air flow speed, and wind deflector angle of (P＝67.5°) can reduce DR. Based on the all variables, a table of the optimal wind deflector angle was recommended according to the wind direction.
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Wu, Yi-min, and 吳逸民. "Influences of Surrounding Building on Wind-driven Natural Ventilation." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/18580739424492035492.
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碩士國立中央大學
土木工程研究所
100
In densely-populated areas, where buildings are grouped closely together, wind-driven ventilation is strongly influenced by the surrounding structures. The sheltering effect of the surrounding built-up environment can reduce the wind speed and wind-driven ventilation rate. This study used a three-dimensional Computational Fluid Dynamics (CFD) model to investigate the influences of adjacent building on wind-driven natural ventilation of the downwind building. The influences of building depth, height, width and spacing between the buildings were systemically studied. The simulation results demonstrated that the ventilation rate decreases as the building depth increases, and the influence of building width on the cross ventilation rate of a single building is insignificant. When two identical buildings placed in tandem arrangement, the ventilation rate of downwind building, compared to that of a single building, was notably reduced by 50% when the spacing between two buildings is less than three times of building height. The numerical results also demonstrate that the ventilation rate of downwind building will be significantly reduced when the upwind building width and height was Wu/Wb≧1.5or Hu/Hb≧1.5.
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Lo, Liang Chung James. "Predicting wind driven cross ventilation in buildings with small openings." Thesis, 2012. http://hdl.handle.net/2152/ETD-UT-2012-08-6006.
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Designing wind driven cross ventilation for a building is challenging due to the dynamic characteristics of wind. While numerous studies have studied various aspects of cross ventilation, few have had an opportunity to examine the topic with a holistic approach utilizing multiple research techniques. Thus, this dissertation combined three different investigation methods: wind tunnel analysis, full scale experiments and computational fluid dynamics (CFD) to examine the physics of wind driven cross ventilation.
Following the systematic approaches of the three methods, this study first conducted full scale measurements of wind properties, façade pressures, air flow rates through small window openings, and tracer gas concentrations in a multi-zone test house. Secondly, a scaled model of the test house was studied in a boundary layer wind tunnel (BLWT) for its façade pressures and ventilation rate under various wind incident angles. Finally, a CFD model of the test house was simulated under various constraints to determine the factors which affect indoor air distribution during wind driven cross ventilation events.
The full scale experimental results showed a strong correlation between the cross ventilation rate and the wind velocity component normal to the inlet openings. This correlation suggested that the cross ventilation flow rate could be estimated from wind conditions alone. A closer examination of the wind characteristics also revealed that the cyclical pattern of changing wind direction could be impacted by obstructions which are kilometers upwind, suggesting that distant landscapes could have an impact on cross ventilation flows.
The combination of CFD and full scale measurements also showed that local heat sources can generate significant buoyancy driven flow and affect indoor mixing during wind-driven cross ventilation scenarios. Experimentally validated parametric CFD analyses demonstrated the effect of interior heat loads in driving internal airflow, and suggest that a small source (35W/m2) can increase the indoor mixing from less than 1 ACH to 8 ACH between indoor spaces.
Finally, the wind tunnel and CFD coupled analysis was found to predict the cross ventilation flow which was also validated against the full scaled measurements. The prediction, which may only be applicable to similar building types with small openings, showed significant agreement that such method has potential as an innovative design tool for natural ventilation in buildings.text
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Cole, Steven Edward. "Effect of a wind protection device on ventilation fan performance." 1988. http://hdl.handle.net/2097/22196.
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