Academic literature on the topic 'Water tunnel experiments'
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Journal articles on the topic "Water tunnel experiments":
1
Makoto, Yamaguchi, Kiwata Takahiro, Kono Takaaki, and Ueno Toshiyuki. "1192 WATER TUNNEL EXPERIMENTS ON TRANSVERSE VIBRATION OF A CANTILEVERED PRISM." Proceedings of the International Conference on Jets, Wakes and Separated Flows (ICJWSF) 2013.4 (2013): _1192–1_—_1192–6_. http://dx.doi.org/10.1299/jsmeicjwsf.2013.4._1192-1_.
2
Cutler, Paul M. "Modelling the evolution of subglacial tunnels due to varying water input." Journal of Glaciology 44, no. 148 (1998): 485–97. http://dx.doi.org/10.3189/s002214300000201x.
Abstract:
AbstractThe time evolution of a subglacial tunnel cross-section is examined usine a two-dimensional finite-element ice-flow model coupled to an idealized drainage system. Simulations are driven by physically based calculations of surface water-input variations at Slorgiaciaren, Sweden. Highlights of the model are its ability to handle unsteady conditions and irregular tunnel shapes. Agreement between modelled water pressure and borehole water levels is good. The following conclusions are reached: (i) Tunnels adapt to fluctuating inflow on time-scales of days. Storms, during which effective pressure ranges from 0 to 0.9 MPa, cause significant adjustments but daily fluctuations due solely to melt-water inflow are minor, (ii) Open-channel flow may become commonplace late in the ablation season, (iii) Initial tunnel shape influences subsequent tunnel evolution and seasonal water-pressure variation. Over the course of a summer, tunnels retain some of their initial shape, though in all experiments the width-to-height ratio increased with time, (iv) Tunnel contraction forms broad low tunnels. However, (v) given two tunnels of equal initial area, the higher narrower one expands more rapidly. Thus, more semi-circular tunnels may capture How from broader neighbours early in the summer.
3
Cutler, Paul M. "Modelling the evolution of subglacial tunnels due to varying water input." Journal of Glaciology 44, no. 148 (1998): 485–97. http://dx.doi.org/10.1017/s002214300000201x.
Abstract:
AbstractThe time evolution of a subglacial tunnel cross-section is examined usine a two-dimensional finite-element ice-flow model coupled to an idealized drainage system. Simulations are driven by physically based calculations of surface water-input variations at Slorgiaciaren, Sweden. Highlights of the model are its ability to handle unsteady conditions and irregular tunnel shapes. Agreement between modelled water pressure and borehole water levels is good. The following conclusions are reached: (i) Tunnels adapt to fluctuating inflow on time-scales of days. Storms, during which effective pressure ranges from 0 to 0.9 MPa, cause significant adjustments but daily fluctuations due solely to melt-water inflow are minor, (ii) Open-channel flow may become commonplace late in the ablation season, (iii) Initial tunnel shape influences subsequent tunnel evolution and seasonal water-pressure variation. Over the course of a summer, tunnels retain some of their initial shape, though in all experiments the width-to-height ratio increased with time, (iv) Tunnel contraction forms broad low tunnels. However, (v) given two tunnels of equal initial area, the higher narrower one expands more rapidly. Thus, more semi-circular tunnels may capture How from broader neighbours early in the summer.
4
GONZALEZ-RODRIGUEZ, DAVID, and OLE SECHER MADSEN. "Boundary-layer hydrodynamics and bedload sediment transport in oscillating water tunnels." Journal of Fluid Mechanics 667 (November 1, 2010): 48–84. http://dx.doi.org/10.1017/s0022112010004337.
Abstract:
Oscillating water tunnels are experimental facilities commonly used in coastal engineering research. They are intended to reproduce near-bed hydrodynamic and sediment transport phenomena at a realistic scale. In an oscillating water tunnel, a piston generates an oscillatory motion that propagates almost instantaneously to the whole tunnel; consequently, flow is uniform along the tunnel, unlike the propagating wave motion in the sea or in a wave flume. This results in subtle differences between the boundary-layer hydrodynamics of an oscillating water tunnel and of a propagating wave, which may have a significant effect in the resulting sediment transport. In this paper, we present a zeroth-order analytical model of the turbulent boundary-layer hydrodynamics in an oscillating water tunnel. By using a time-varying eddy viscosity and by accounting for the constraints arising from the tunnel's geometry, the model predicts the oscillating water tunnel hydrodynamics and yields analytical expressions to compute bed shear stresses for asymmetric and skewed waves, both in the absence or presence of an imposed current. These expressions are applied to successfully quantify bedload sediment transport in oscillating water tunnel experiments.
5
Aziz, Fahrurrozi, Katrine A. Stewart, and Sylvie Jenni. "Early Growth of Muskmelon in Mulched Minitunnels Containing a Thermal Water Tube. I. Carbon Dioxide Concentrations in the Tunnel." Journal of the American Society for Horticultural Science 126, no. 6 (November 2001): 757–63. http://dx.doi.org/10.21273/jashs.126.6.757.
Abstract:
Temperature modification is the most investigated environmental factor considered to affect muskmelon (Cucumis melo L. Reticulatus Group) growth in a mulched minitunnel production system. Until now, effects on CO2 concentrations within the tunnel have been ignored. Experiments on production of `Earligold' netted muskmelon were conducted in 1997, 1998, and 1999 to determine daily CO2 concentrations for 10 mulched minitunnel and thermal water tube combinations. Carbon dioxide concentrations under nonperforated (clear or infrared-blocking polyethylene) tunnels were significantly higher (three to four times) than that of ambient air. Soil respiration under the plastic mulch was primarily responsible for increased CO2 levels in the tunnel. Daily CO2 concentrations in the tunnels varied little during early muskmelon growth, but fluctuated widely as the plants developed. Ventilation significantly decreased CO2 concentrations in the tunnels but levels remained significantly above the control and perforated tunnel treatments. When using mulched minitunnels for muskmelon production, daily CO2 concentrations should be recognized as a significant factor influencing growth.
6
Huang, Zhangkai, Meixia Chen, Ting Wang, Huachang Cui, and Wenkai Dong. "Numerical Investigation of Background Noise in a Circulating Water Tunnel." Machines 11, no. 8 (August 18, 2023): 839. http://dx.doi.org/10.3390/machines11080839.
Abstract:
The presence of excessive background noise in hydrodynamic noise experiments conducted in circulating water tunnels can significantly impact the accuracy and reliability of experimental test results. To address this issue, it is crucial to evaluate and optimize the background noise during the design stage. In this research, acoustic field model and fluid–solid coupling numerical calculation model of circulating water tunnels are established. Utilizing the finite element method, we analyze the flow noise and flow-excited noise resulting from wall pressure pulses in the circulating water tunnel. Furthermore, we conduct a noise contribution analysis and explore strategies for structural vibration noise control. The results demonstrate that both flow noise and flow-excited noise decrease with increasing frequency, with flow-excited noise being the primary component of the tunnel’s background noise. The presence of resonant peaks significantly contributes to the elevated flow-excited noise levels. Moreover, enhancing structural stiffness and damping proves less effective in suppressing low-frequency peaks. Additionally, employing sound measurement pods suspended from the side of the test section for noise measurement exhibits a high error rate at low frequencies. This research provides insights into optimizing background noise in water tunnels, thereby informing future enhancements in tunnel design.
7
Kerwin, Justin E. "The MIT Marine Hydrodynamics Water Tunnel—A 53rd Anniversary Celebration." Marine Technology and SNAME News 31, no. 03 (July 1, 1994): 183–94. http://dx.doi.org/10.5957/mt1.1994.31.3.183.
Abstract:
Fifty-three years ago, Professor Frank M. Lewis presented a paper entitled "Propeller Testing Tunnel at the Massachusetts Institute of Technology," at the spring meeting of SNAME. The tunnel is still there, although its name is changed, and its appearance2 is very different. However, the goals of the laboratory are still very much the same—to conduct innovative experiments designed to learn more about the fundamentals of the flow around propellers and other objects of interest to ocean engineers. This paper presents a historical review of many of the varied experiments conducted since the tunnel was completed, with emphasis on several recent projects. This will include an account of the application of the Laser Doppler Velocimeter to map the flow around propellers, underwater vehicles and cavitating foil sections, as well as the development of an apparatus to study the response of a two-dimensional foil to high-frequency gusts. The combination of experiments and theory is discussed, and some thoughts on future experiments are presented.
8
Bao, Tong, Sulei Zhang, Chang Liu, and Qing Xu. "Experimental Study on the Effect of Hydraulic Deterioration of Different Drainage Systems on Lining Water Pressure." Processes 10, no. 10 (September 30, 2022): 1975. http://dx.doi.org/10.3390/pr10101975.
Abstract:
With the increasing operation time of tunnels, the drainage system cannot fulfil its proper function as a result of the deterioration of traditional waterproof and drainage systems (TWDS), such as the blockage of drainage blind pipes and the failure of drainage boards. Therefore, the lining bears a high water pressure and even causes disasters such as tunnel leakage and lining cracking. An effective solution to mitigate these issues is to adjust the tunnel drainage scheme. In view of this, a composite waterproof and drainage system (CWDS) is proposed in this paper. To verify the effectiveness of the proposed system, a series of model experiments were conducted to study the change law of the seepage field of two drainage systems under different blockage conditions. The study results showed that longitudinal blind pipe blockage caused a more significant increase in water pressure than circular blind pipe blockage. In the case of blind pipe blockage, the water pressure of the TWDS tunnels rise rapidly, while the CWDS tunnels could effectively drain and reduce pressure.
9
Machado Jorge, Vitor Augusto, Pedro Daniel de Cerqueira Gava, Juan Ramon Belchior de França Silva, Thais Mancilha, Waldir Vieira, Geraldo José Adabo, and Cairo Lúcio Nascimento. "Analytical Approach to Sampling Estimation of Underwater Tunnels Using Mechanical Profiling Sonars." Sensors 21, no. 5 (March 9, 2021): 1900. http://dx.doi.org/10.3390/s21051900.
Abstract:
Hydroelectric power plants often make use of tunnels to redirect the flow of water to the plant power house. Such tunnels are often flooded and can span considerable distances. Periodical inspections of such tunnels are highly desirable since a tunnel collapse will be catastrophic, disrupting the power plant operation. In many cases, the use of Unmanned Underwater Vehicles (UUVs) equipped with mechanical profiling sonars is a suitable and affordable way to gather data to generate 3D mapping of flooded tunnels. In this paper, we study the resolution of 3D tunnel maps generated by one or more mechanical profiling sonars working in tandem, considering synchronization and occlusion problems. The article derives the analytical equations to estimate the sampling of the underwater tunnels using mechanical profiling sonars (scanning sonars). Experiments in a simulated environment using up to four sensors simultaneously are presented. We also report experimental results obtained by a UUV inside a large power plant tunnel, together with a first map of this environment using a single sonar sensor.
10
Lai, Leyi, Yuanzhu Zhang, and Kuixin Xu. "Prediction of Wet Area of Underwater Tunnel Lining." Buildings 14, no. 2 (February 2, 2024): 408. http://dx.doi.org/10.3390/buildings14020408.
Abstract:
The issue of water seepage poses a significant challenge in tunnel infrastructure. Wet areas are commonly used to evaluate the degree of water seepage in tunnel projects. To investigate the feasibility for numerical simulation to predict a wet area, we selected concrete test blocks with two types of defects—holes and cracks—as the research specimens. Numerical models for various seepage conditions were constructed using TOUGH2, and the results were validated through laboratory experiments. Additionally, the Shenjiamen Subsea Tunnel was simplified into a numerical model, employing TOUGH2 to forecast its future wet area performance within the scope of national standards. The outcomes of our research revealed that point seepage and line seepage exhibited circular and elliptical morphologies, respectively. Moreover, external water pressure and defect size exerted a significant influence on the expansion of the wet area. Notably, the impact of crack width surpassed that of hole diameter. Encouragingly, the numerical models generated using TOUGH2 for unsaturated concrete demonstrated excellent agreement with laboratory test results concerning the geometry, size, and pattern of the wet area. These findings signified the potential of TOUGH2 numerical simulation as a valuable tool in predicting the lifespan of tunnels.
Dissertations / Theses on the topic "Water tunnel experiments":
1
Munro, Cameron. "Water tunnel validation and experiments at high angles of attack for aircraft conceptual design /." Linköping : Univ, 2003. http://www.bibl.liu.se/liupubl/disp/disp2002/tek847s.pdf.
2
Gluck, Jeffrey Weston, and Jeffrey Weston Gluck. "Water Tunnel Experiments on Span-wise Variation of Laminar Separation Bubbles for Swept and Unswept Wings using Particle Image Velocimetry." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/621851.
Abstract:
An inverted airfoil mounted above a flat plate was used to create laminar separation bubbles on a flat plate in water tunnel experiments at low Reynolds numbers. Boundary layer suction ensured that the flow remained attached to the wing. Two-dimensional PIV measurements were used to qualitatively and quantitatively characterize the spanwise bubble variation on an unswept wing and on the same wing featuring a 22 degree sweep. The separation bubbles were recorded at varied span-wise locations in a 31.5 cm wide region of the flow. The limitations of this measurement region were dictated by the focal length of the laser optic used for PIV measurements. The straight wing exhibited approximately uniform time averaged separation positions across the span of the wing. The reattachment locations varied only slightly which was expected due to the transition to turbulent flow before reattachment. A form of bubble "breathing" was observed in the laminar separation bubbles on the straight wing and is believed to have affected the mean reattachment locations for two data points recorded. The shedding frequencies on the straight wing were slightly higher than those obtained from CFD simulations. The swept wing planform showed significantly more variation in the mean separation and reattachment locations with respect to the leading edge of the wing. There is a general trend of the separation locations moving upstream in the direction of the aft leading edge. The reattachment points are shown to move downstream as the separation points move upstream relative to the leading edge and visa versa, displaying an inverse relationship between the two. The bubble lengths were found to be slightly longer on the swept wing compared to the straight wing usually by about 10%. The shedding frequencies on the swept wing were found to be lower than the straight wing. The quality of flow in the water tunnel may have degraded over time, showing signs of increased free stream turbulence. After data collection, it was also discovered that the boundary layer suction on the wing was not constant at all span-wise locations. It is believed that the introduction of wing sweep intensified the effect of insufficient suction on the structure of the bubbles observed. The present results were in agreement with previous research for bubble structure but the dynamic instabilities were found to differ slightly.
3
Ciccone, Brianne N. "Modeling of Evaporative Losses in Industrial Pasteurization." Youngstown State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1339587036.
4
Rolland, Romain. "Caractérisation de l'interaction fluide-structure d'un assemblage de coeur de réacteur sous forçage sismique." Electronic Thesis or Diss., Institut polytechnique de Paris, 2022. http://www.theses.fr/2022IPPAE005.
Abstract:
Dans le cadre des études de sûreté, il est nécessaire de disposer de modèles validés des forces fluides s’exerçant sur des assemblages combustibles en cas de séisme. Dans la technologie REP (réacteur à eau pressurisée) utilisée en France, les assemblages sont constitués de faisceaux de crayons cylindriques disposés en réseau carré et soumis à un écoulement axial. En cas de séisme, ces assemblages sont soumis à des oscillations latérales. Ces vibrations peuvent mener à la déformation des assemblages. Des campagnes d’essais sur assemblage combustible réel ont été réalisées et ont mis en évidence l'existence de forces fluides dissipatives dont l'évolution et la répartition spatiale reste encore mal documentées. L'objectif des présents travaux est de contribuer à la description de ces forces en dynamique. Le modèle de référence pour la description de la dynamique des structures élancées sous écoulement axial est le modèle de TLP (Taylor-Lighthill-Païdoussis). Dans la littérature ce modèle a été validé pour une structure très proche du faisceau de cylindres. Des études statiques réalisées sur un cylindre dans un faisceau ont montré une influence non négligeable des extrémités sur les efforts exercés par le fluide sur la structure. La littérature propose peu de cas de validation du modèle TLP pour des structures plus complexes et proches d'un assemblage combustible. Afin d'évaluer la capacité du modèle à décrire les efforts fluides s'exerçant sur une structure plus proche d'un assemblage combustible, un nouveau banc d'essai a été conçu et mis en service. Ce banc d'essais permet de faire osciller latéralement un faisceau de cylindre 5 x 5 muni de grilles à chaque extrémité dans un écoulement axial. Des mesures de force au niveau de chaque grille donne accès à la résultante d'effort de la structure. Un modèle numérique complète cette approche expérimentale et donne accès à la répartition des efforts dans la structure. Les forces obtenues expérimentalement semble indiquer un effet important des grilles. Les forces issues des simulations confortent les observations faites sur un faisceau de cylindres et apportent de nouveaux éléments sur la répartition des efforts locaux ainsi que l'influence des extrémitésWithin the framework of safety studies, it is necessary to have validated models of the fluid forces exerted on fuel assemblies in the event of an earthquake. In the PWR (Pressurized Water Reactor) technology used in France, fuel assemblies are made of cylindrical rods bundles arranged in a square array and subjected to an axial flow. In case of an earthquake, these assemblies are subjected to lateral oscillations. These vibrations can lead to the deformation of the assemblies. Test campaigns on real fuel assemblies have been carried out and have revealed the existence of dissipative fluid forces whose evolution and spatial distribution are still poorly documented. The objective of the present work is to contribute to the description of these forces in dynamics. The reference model for the description of the dynamics of slender structures under axial flow is the TLP model (Taylor-Lighthill-Païdoussis). In the literature this model has been validated for a structure very close to the cylinder bundle. Static studies performed on a cylinder in a bundle have shown a non-negligible influence of the extremities on the forces exerted by the fluid on the structure. The literature proposes few validation cases of the TLP model for more complex structures close to a fuel assembly. In order to evaluate the capacity of the model to describe the fluid forces exerted on a structure closer to a fuel assembly, a new test bench was designed and put into service. This test rig allows to laterally oscillate a cylinder bundle 5 x 5 with grids at each end in an axial flow. Force measurements at each grid give access to the resultant force of the structure. A numerical model completes this experimental approach and gives access to the distribution of forces in the structure. The forces obtained experimentally seem to indicate an important effect of the grids. The forces obtained from the simulations confirm the observations made on a bundle of cylinders and bring new elements on the distribution of the local forces as well as the influence of the extremities
5
Bassan, Rodrigo Augusto [UNESP]. "Visualização experimental de escoamentos no interior de canais munidos de protuberâncias parietais." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/136024.
Abstract:
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000859557.pdf: 4186035 bytes, checksum: 8bdc39e13acd7f3473cf85fc408591fa (MD5)Neste trabalho realiza-se um estudo do escoamento no interior de um canal com protuberâncias parietais para números de Reynolds menores que 103. Os ensaios foram conduzidos em um túnel hidrodinâmico vertical. Perfis de velocidade na seção de testes, assim como a intensidade turbulenta do túnel e emissões de vórtices, foram adquiridos por meio da anemometria de fio/filme quente. Técnicas de visualização de escoamentos, também, foram empregadas em diferentes circunstâncias, com três objetivos fundamentais: como ferramenta de análise qualitativa, na identificação de padrões de escoamento; como mecanismo de apoio à realização de medidas experimentais, para auxiliar no correto posicionamento de sondas anemométricas; e, finalmente, como instrumento complementar de análise, para facilitar a interpretação de resultados. Em todos os casos o escoamento foi tratado estritamente bidimensional. Outro fator importante deste trabalho refere-se a reconstrução do túnel hidrodinâmico vertical, o qual situa-se no Laboratório de Visualização de Escoamentos do Departamento de Engenharia Mecânica da UNESP - campus de Ilha Solteira; que com grande empenho dos Professores Edson Del Rio Vieira, Sergio Said Mansur, Técnicos do laboratório e com uma pequena contribuição de minha parte pode-se finalizar esse projeto
In the present work is accomplished a study of the flow within a channel with parietal 3 protuberances for Reynolds numbers less than 10 . The tests were conducted in a hydrodynamic tunnel vertical. Velocity profiles in the test section, as well as the turbulent intensity of the tunnel, vortex emissions were acquired through anemometry wire / hot film. Flow visualization techniques were employed as a tool for qualitative analysis, in the identification of flow patterns, as qualitative analytical tool to identify flow patterns; as a mechanism to support the implementation of experimental measurements, to assist in the correct positioning of airspeed probes; and finally as an additional tool of analysis, to facilitate interpretation of results. In every case the disposal was treated dimensional strictly. Another important factor of this work refers to the reconstruction of vertical hydrodynamic tunnel, which is located in the Flow View Laboratory, Department of Mechanical Engineering of UNESP - campus of Single Island; that with great commitment of Teachers Edson Vieira Del Rio, Sergio Said Mansur, lab technicians and a small contribution from me you can finish this project
6
Bassan, Rodrigo Augusto. "Visualização experimental de escoamentos no interior de canais munidos de protuberâncias parietais /." Ilha Solteira, 2015. http://hdl.handle.net/11449/136024.
Abstract:
Orientador: Sérgio Said MansurCo-orientador: Edson Del Rio Vieira
Banca: André Luiz Seixlack
Banca: Odenir de Almeida
Resumo: Neste trabalho realiza-se um estudo do escoamento no interior de um canal com protuberâncias parietais para números de Reynolds menores que 103. Os ensaios foram conduzidos em um túnel hidrodinâmico vertical. Perfis de velocidade na seção de testes, assim como a intensidade turbulenta do túnel e emissões de vórtices, foram adquiridos por meio da anemometria de fio/filme quente. Técnicas de visualização de escoamentos, também, foram empregadas em diferentes circunstâncias, com três objetivos fundamentais: como ferramenta de análise qualitativa, na identificação de padrões de escoamento; como mecanismo de apoio à realização de medidas experimentais, para auxiliar no correto posicionamento de sondas anemométricas; e, finalmente, como instrumento complementar de análise, para facilitar a interpretação de resultados. Em todos os casos o escoamento foi tratado estritamente bidimensional. Outro fator importante deste trabalho refere-se a reconstrução do túnel hidrodinâmico vertical, o qual situa-se no Laboratório de Visualização de Escoamentos do Departamento de Engenharia Mecânica da UNESP - campus de Ilha Solteira; que com grande empenho dos Professores Edson Del Rio Vieira, Sergio Said Mansur, Técnicos do laboratório e com uma pequena contribuição de minha parte pode-se finalizar esse projeto
Abstract: In the present work is accomplished a study of the flow within a channel with parietal 3 protuberances for Reynolds numbers less than 10 . The tests were conducted in a hydrodynamic tunnel vertical. Velocity profiles in the test section, as well as the turbulent intensity of the tunnel, vortex emissions were acquired through anemometry wire / hot film. Flow visualization techniques were employed as a tool for qualitative analysis, in the identification of flow patterns, as qualitative analytical tool to identify flow patterns; as a mechanism to support the implementation of experimental measurements, to assist in the correct positioning of airspeed probes; and finally as an additional tool of analysis, to facilitate interpretation of results. In every case the disposal was treated dimensional strictly. Another important factor of this work refers to the reconstruction of vertical hydrodynamic tunnel, which is located in the Flow View Laboratory, Department of Mechanical Engineering of UNESP - campus of Single Island; that with great commitment of Teachers Edson Vieira Del Rio, Sergio Said Mansur, lab technicians and a small contribution from me you can finish this project
Mestre
7
Albrektsson, Joakim. "Durability of fire exposed concrete : Experimental Studies Focusing on Stiffness & Transport Properties." Licentiate thesis, KTH, Betongbyggnad, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-168386.
Abstract:
Road and rail tunnels are important parts of the modern infrastructure. High strength concrete (HSC) is commonly used for tunnels and other civil engineering structures, since it allows high load carrying capacity and long service life. In general, Swedish road and rail tunnels should be designed for a service life of 120 years. However, HSC has shown to be sensitive to severe fires in the moist tunnel environment, i.e., fire spalling may occur. Extensive research shows that addition of polypropylene (PP) fibres in the fresh concrete mix significantly reduces the risk of fire spalling. The durability of a concrete structure is mainly governed by the transport properties. Further, experimental studies aimed at understanding the protective mechanism of PP fibres indicate that fluid transport increases in connection with the melting temperature of such fibres. This might reduce the durability of fire exposed concrete with addition of PP fibres. This study aims to investigate whether the use of PP fibres has any significant effect on the durability of moderate fire exposed concrete structures. The experimental study focused on transport properties related to durability and stiffness reduction of fire exposed civil engineering concrete with and without addition of PP fibres. The study consists of three parts; (i) unilateral fire exposure in accordance with the standard time-temperature curve (Std) and a slow heating curve (SH), (ii) uniformly heating of non-restrained samples to 250oC, and (iii) moderate unilateral fire exposure, 350oC, of restrained samples. Changes in material properties caused by the fire exposure were studied by means of ultrasonic pulse velocity, full field-strain measurements during uniaxial compression core tests, polarization and fluorescence microscopy (PFM), water absorption and non-steady state chloride migration. The study shows that fire exposure influences different properties of importance for load carrying capacity and durability. To get a clear image of the fire damage one has to combine different test methods during damage assessments. Transport properties of concrete both with and without addition of PP fibres were considerably affected even at moderate fire exposure. Hence, the service life might be reduced. All series with addition of PP fibres exhibited higher water absorption compared to the series without PP fibres. The practical importance of this might, however, be small since also the water absorption of concrete without PP fibres was considerably affected for the fire scenarios considered in this study. Behind the fire exposed surface, i.e., between 30 and 60 mm, no change in water absorption was observed for concrete without PP fibres. However, higher water absorption of the series with addition of PP fibres was observed. Indicative fire tests aimed to evaluate the resistance to fire spalling during a subsequent severe fire was also conducted. The concretes with addition of PP fibres showed no signs of fire spalling, while progressive spalling was observed for the concrete without PP fibres.QC 20150603
8
Briançon-Marjollet, Laurence. "Couches-limites, germes et cavités en interaction : étude physique." Grenoble 1, 1987. http://www.theses.fr/1987GRE10119.
Abstract:
Etude en tunnel hydrodynamique de l'influence de la teneur en germes libres de l'eau sur la cavitation se developpant sur un profil bidimensionnel en ecoulement permanent. On etudie le type de cavitation (poche attachee ou bulle separee) et son developpement en fonction de l'incidence du profil, du nombre de reynolds, du parametre de cavitation et de la concentration en germes libres. On determine des zones d'influence des germes. On montre l'importance de la couche limite et du nombre de germes actifs dans la determination du debut de cavitation et du type de cavitation. Application aux machines tournantes
9
Rouland, Eric. "Etude et développement de la technique de vélocimétrie par intercorrélation d'images de particules. Application aux écoulements en tunnel hydrodynamique." Rouen, 1994. http://www.theses.fr/1994ROUES078.
Abstract:
La vélocimétrie par intercorrélation d'images de particules (V. I. I. P. ) a fait l'objet d'un développement complet ayant pour but l'étude d'écoulements dans un tunnel hydrodynamique. Elle consiste en une analyse bidimensionnelle par intercorrélation (corrélation-croisée) de deux images prises simultanément par un capteur CCD standard. Ces images sont obtenues en éclairant, par un plan laser, des particules préalablement ensemencées dans l'écoulement. L'algorithme de corrélation-croisée a été comparé au traitement généralement utilisé : l'autocorrélation, et ceci à l'aide d'un programme générateur d'images simulées. Cette comparaison montre que l'intercorrélation d'images séparées résout à la fois le problème du signe et des mesures de vitesse autour de zéro, cela permet de bénéficier d'une dynamique de vitesse maximum dans la fenêtre d'analyse. Elle met aussi en évidence qu'on peut accepter des densités de particules beaucoup plus élevées et du même ordre que la densité utilisée pour la visualisation par tomographie. Enfin, nous abordons l'application de la méthode aux écoulements dans un tunnel hydrodynamique autour de profils immergés (cylindre, hélice). Nous montrons qu'en dépit d'un ensemencement utilisant des microbulles d'air de différents diamètres et en faible concentration, la V. I. I. P. Permet d'étudier les écoulements propres au tunnel. Dans ce contexte, les informations instantanées, obtenues après l'utilisation de critères de validation de vecteurs vitesse et l'application de post-traitements, permettent ainsi l'analyse de phénomènes de fluctuation spatiale qui apparaissent par exemple dans le sillage d'un cylindre.
10
Kushwaha, Pushpendra Kumar. "Experimental and Numerical Study on Boundary Layer Growth in Wind Tunnel." Thesis, 2017. http://ethesis.nitrkl.ac.in/8768/1/2017_MT_PK_Kushwaha.pdf.
Abstract:
When a real fluid flow passes over the surface of a flat plate, the velocity of the fluids on the surface of the object becomes same as that of the object. If object is at rest, the fluid will also have zero velocity because of no slip condition at the boundary. Away from the boundary the velocity increase gradually and reaches to free stream velocity and hence there exists a region closed to the object where velocity gradient exists, this region is known as boundary layer region. The flow in the boundary layer is viscous and rotational. Due to viscous effect shear stress is developed inside the boundary layer, above the boundary layer region the flow is non viscous. Study of boundary layer is vital for design of streamline bodies such as air foil. Generally most of wind tunnel is mainly designed for the study of aeronautic action with laminar flow and produces low depth of boundary layer due to lack of turbulence intensity in test section of wind tunnel.
This thesis describes how thick boundary layer can be produced in a short wind tunnel. Several type of thickening (passive) devices are used to increase the boundary layer growth in low speed wind tunnel. This project is a study of four different passive devices (spire, mat, square and diamond blocks) separately and in various combination so that boundary layer can be increased and analyzes the effect of these roughness elements on boundary layer parameter using velocity profile at various free stream velocity at various sections in wind tunnel. This thesis is also used to simulate the atmospheric boundary layer in wind tunnel with a short test section (8m ×.6m×.6m). This project presents the design, computation analysis and experimental study of passive device of different configuration.
Books on the topic "Water tunnel experiments":
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Canada. Defence Research Establishment Atlantic. Flow Visualization Experiments with Submarine Models in A Water Tunnel. S.l: s.n, 1986.
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J, Peake D., and Ames Research Center, eds. Vortex breakdown and control experiments in the Ames-Dryden water tunnel. Moffett Field, Calif: National Aeronautics and Space Administration, Ames Research Center, 1987.
Book chapters on the topic "Water tunnel experiments":
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Gloerfeld, Mark, Markus Schremb, Antonio Criscione, Suad Jakirlic, and Cameron Tropea. "Impact of Supercooled Drops onto Cold Surfaces." In Fluid Mechanics and Its Applications, 311–32. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-09008-0_16.
Abstract:
AbstractIce accretion resulting from the impact of supercooled water drops is a hazard for structures exposed to low temperatures, for instance aircraft wings and wind turbine blades. Despite a multitude of studies devoted to the involved phenomena, the underlying physical processes are not yet entirely understood. Hence, modelling of the conditions for ice accretion and prediction of the ice accretion rate are presently not reliable. The research conducted in this study addresses these deficiencies in order to lend insight into the physical processes involved. While presenting an overview of results obtained during the first funding periods of this project, new results are also presented, relating to the impact of supercooled drops onto a cold surface in a cold air flow. The experiments are conducted in a dedicated icing wind tunnel and involve measuring the residual mass after impact of a liquid supercooled drop exhibiting corona splash as well as the impact of dendritic frozen drops onto a solid surface.
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Gao, Ang, Xiufeng Wu, Shiqiang Wu, Hongpeng Li, Jiangyu Dai, and Fangfang Wang. "Study on Wind Waves Similarity and Wind Waves Spectrum Characteristics in Limited Waters." In Lecture Notes in Civil Engineering, 1220–35. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-6138-0_107.
Abstract:
AbstractWind waves is an important factor affecting navigation safety and water environment in limited waters such as lakes and bays. Wind wave spectrum represents the frequency domain features of wind waves and has always been the focus of research. Based on the field observation and flume experimental method, the system analysis of similarity of two kinds of situations, discussed nonlinear response of the relationship of the spectral shape parameter of balance field α, β and wind waves basic frequency between factors like wind speed, wind blowing fetch and water depth. By means of wind tunnel flume and prototype observation data of nonlinear regression analysis, The relation formulas of wind wave frequency prediction considering the comprehensive influence of wind speed, wind blowing fetch and water depth is established. Relevant research is of great significance for revealing the evolution characteristics of wind waves in limited waters and guiding navigation safety and water environment management.
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Neu, Gerrit Emanuel, Florian Christ, Tagir Iskhakov, Christina Krikelis, Diego Nicolás Petraroia, Sven Plückelmann, Maximilian Schoen, et al. "Tunnel Linings." In Interaction Modeling in Mechanized Tunneling, 253–327. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-24066-9_5.
Abstract:
AbstractIn this chapter, important research results for the development of a robust and damage-tolerant multimaterial tunnel lining are presented. This includes the production, design and optimization of fiber-reinforced hybrid segmental lining systems based on numerical models and experimental investigations under tunneling loads. In addition, novel tail void grouting materials are developed and optimized regarding their infiltration and hardening behavior while taking the interaction with the surrounding ground into account. In order to expand the applicability of mechanized tunneling regarding soils characterized by significant swelling potential due to water uptake by clay minerals, a deformable segmental lining system is presented. The risk of damage due to high localized loads is reduced by the integration of additional radial protective layers on the lining segments and a compressible annular gap grout, which protect the tunnel structure by undergoing high deformations after reaching a certain yielding load. However, the deformability of such support systems affects the distribution of the stresses around the tunnel which governs the magnitude and buildup of the swelling pressure in the soil. Therefore, the development of damage tolerant lining systems requires a material and structural design which ensures an optimal soil-structure interaction through a synergy of computational and experimental techniques.
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Sha, Haifei, Lili Fan, Shiqiang Wu, Hui Zhou, and Huiling Chen. "Experimental Studies on Aeration Performance of Hydraulic Tunnel Excavation." In Advances in Water Resources and Hydraulic Engineering, 646–50. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-89465-0_113.
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Zalrusli, M. I., A. Rahim, K. Ramanathan, R. A. Abdullah, T. L. Goh, and W. M. W. Ibrahim. "Experimental Analysis of Geological Structure to the Water Intrusion into Tunnel." In Springer Proceedings in Physics, 489–99. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-9267-4_49.
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Wu, Jianqiu, Lei Han, and Xingjie Fang. "Experimental and numerical study on the bending behavior of cup joints of prefabricated utility tunnel." In Water Conservancy and Civil Construction Volume 1, 413–21. London: CRC Press, 2023. http://dx.doi.org/10.1201/9781003450818-56.
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Ledesma, A., and A. Gens. "Inverse Analysis of a Tunnel Excavation Problem from Displacement and Pore Water Pressure Measurements." In Material Identification Using Mixed Numerical Experimental Methods, 163–72. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-009-1471-1_17.
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Lan, Yujie, Xinyi Liu, Haifeng Chen, Xineng Yan, Shanxin Zhou, Xiaosong Li, and Longfei Chen. "Numerical Studies on the Heat Insulation and Smoke Control Effect of Water Mist Screen Under Longitudinal Ventilation in Bifurcated Tunnel." In Computational and Experimental Simulations in Engineering, 473–88. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-42515-8_33.
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Anjali, R., S. Anandha Kumar, Jaswanth Gangolu, and R. Abiraami. "Experimental Study on Self-Healing of Micro-Cracks in Concrete with Combination of Environmentally Friendly Bacteria." In Sustainable Structures and Buildings, 95–109. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-46688-5_7.
Abstract:
AbstractMicro-cracks in constructions are unavoidable due to freezing, thawing, and shrinkage in concrete, as well as when concrete is exposed to the seafloor, on offshore platforms, or in tunnels and sewage pipes. This exposure also has an impact on the durability and service life of concrete. Standard healing materials are not long-lasting and are difficult to mend fine cracks with. According to new research, bacterial concrete is an effective approach for repairing concrete and boosting its longevity. The problem has been reduced using calcite-producing microorganisms that do not pollute the environment and are sustainable to produce. In the presence of carbonate ions, bacteria release calcium precipitate, a process known as bio-calcification. This study includes four blends as (1) normal concrete, (2) Bacillus cereus with normal concrete, (3) Bacillus subtilis with normal concrete, and (4) combined cereus and subtilis with normal concrete. Blend 4 provided the lowest slump value of 70 mm, the highest splitting tensile strength of 2.83 MPa, and the highest flexural strength of 4.37 MPa. This combination was more sustainable and cost-effective because it used less water and cement. Blend 4’s self-healing ability was remarkable, as the microcracks were cured after 7 days. Similarly, Blend 3 had a higher compressive strength of 33 MPa.
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Weise, David R., Timothy J. Johnson, Tanya L. Myers, Wei Min Hao, Stephen Baker, and Javier Palarea-Albaladejo. "A comparison of two methods to measure pyrolysis gases in a wind tunnel and in prescribed burns." In Advances in Forest Fire Research 2022, 483–87. Imprensa da Universidade de Coimbra, 2022. http://dx.doi.org/10.14195/978-989-26-2298-9_74.
Abstract:
Pyrolysis products from wildland fuels are typically measured under tightly controlled conditions using fuels which have been processed to remove water content and physical shape. Different instruments can be used to identify and quantify the composition of these gases. Measurement of pyrolysis gases under conditions typical of wildland fires has seldom occurred. We used FTIR spectroscopy and GC/FID analysis to measure pyrolysis gases produced in wind tunnel experiments and small prescribed burns in longleaf pine needle fuel beds with live shrubs. Use of compositional data techniques on the 8 common gases measured by both methods showed that the compositions were affected by the measurement method and interaction between method and location was significant.
Conference papers on the topic "Water tunnel experiments":
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Kremheller, Andreas, and Hermann Fasel. "Water Tunnel Experiments on Three Dimensional Separation Bubbles on a Flat Plate." In 40th Fluid Dynamics Conference and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2010. http://dx.doi.org/10.2514/6.2010-4738.
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Wilson, Michael. "Simulation of Ship Wakes in Water Tunnel Cavitation Testing of Models." In SNAME 22nd American Towing Tank Conference. SNAME, 1989. http://dx.doi.org/10.5957/attc-1989-005.
Abstract:
Reliable cavitation testing of ship propulsors requires accurate modelling of the ship wake velocity field. This paper presents a progress report on efforts at the David Taylor Research Center (DTRC) to generate properly shaped velocity patterns in a water tunnel by means of partial length afterbody models. A survey of references is presented on the general topic of applications and techniques of wake simulation in water tunnels using a variety of means, including screens mounted normal to the tunnel stream; partial length (dummy model) hull representations; and full length geometrically scaled hull models. Three recent examples are described in some detail of successful wake-generating bodies designed for experiments conducted in the DTRC 36-inch Variable Pressure Water Tunnel. The wakes of these examples are taken in order of increasing degree of difficulty. In each case, there is a discussion of the target wake, the body design considerations, and the quality of the resultant simulated wake.
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Freund, Jr., G. A., F. M. Dickey, R. Elangovan, M. D. Breer, and M. Papadakis. "Automated Optical Instrument For Extracting Water Droplet Impingement Data From Wind Tunnel Experiments." In 31st Annual Technical Symposium. SPIE, 1987. http://dx.doi.org/10.1117/12.978884.
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Yamaguchi, Yuki, and Yuka Iga. "Thermodynamic Effect on Cavitation in High Temperature Water." In ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting collocated with the ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/fedsm2014-21433.
Abstract:
Thermodynamic effect on cavitation appears in cryogenic fluids, refrigerant and high temperature water. The thermodynamic effect is considered to suppress the development of cavitation and improve the performance of hydraulic machinery. However, the actual appearance degree of thermodynamic effect depends on not only thermal property of each fluid but also each hydraulic machinery and its operating condition. So, the clarification of the influence of the flow field with unsteady cavitation on the degree of thermodynamic effect is necessary. In order to investigate thermodynamic effect, many experiments had been conducted with using cryogenic fluids or refrigerant as working fluids. However, there are some difficulties to visualize cryogenic fluids and the experimental results cannot be directly correlated to the condition without thermodynamic effect in same fluid. In the present study, in order to conduct cavitation experiments with and without thermodynamic effect in same fluid, high temperature and high pressure cavitation tunnel had been constructed. The working fluid of this tunnel is water and the free-stream temperature can be varied from room temperature to 140 °C. In the present study, NACA 0015 hydrofoil had been chosen as a cavitator. The extent of thermodynamic effect was estimated through the measurement of temperature in the cavity. The temperature was measured by a thermistor probe which has high accuracy. When the thermodynamic effect appears, temperature depression in the cavity is observed. The maximum temperature depression of cavity about 0.3 K had been measured in water of 80 °C.
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Yoon, Hyun-Se, Dug-Soo Kim, Wu-Joan Kim, Museok Song, Hyoung-Tae Kim, and Suak-Ho Van. "Experimental Study on the Drag Reduction by Injection of Microbubble and Polymer Solution in a Water Tunnel for Water-Borne Vehicles." In ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45651.
Abstract:
Experiments on the friction drag reduction by injecting microbubbles or polymer solutions have been carried out for both a flat wall and an axisymmetric body. In the first setup, the drag reduction on the flat ceiling of a water channel was measured for a fully developed turbulent channel flow by using a newly developed skin friction sensor of floating element type. The effects of key controlling parameters were investigated for higher drag reduction with varying the concentration and the injection rate of the additives. The integrated frictional drag has been reduced up to 25% with the microbubble injection and 50% with the polymer solution injection. The drag reduction for a slender axisymmetric body was also investigated in a cavitation tunnel based on the parameters obtained from the channel experiments.
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Nagaya, Shigeki, Risa Kimoto, Kenji Naganuma, and Takayuki Mori. "Observation and Scaling of Tip Vortex Cavitation on Elliptical Hydrofoils." In ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-33015.
Abstract:
Experimental study on tip vortex cavitation (TVC) was carried out for elliptical hydrofoils with various chord lengths. The purpose of the experiment was to clarify the influences of Reynolds number and water quality on tip vortex cavitation. Experiments were made in a large cavitation tunnel of the Naval Systems Research Center, TRDI/Ministry of Defense Japan. The elliptical hydrofoils tested were NACA 0012 cross section with chord lengths of 500mm, 250mm and 50mm. Reynolds number based on hydrofoil chord length was 2×105 < ReC < 7.4×106. Water quality of the tunnel was characterized by air content and nuclei distribution. Air content of the tunnel was varied between 30% and 80%. Nuclei distribution was measured by a cavitation susceptibility meter (CSM) with center-body venturi. Cavitation inception was determined from high speed video observation. A standard formula, (σL/σS) = (ReL/ReS)n, was applied for the scaling. In the present study, exponent of the scaling law n was found to be 0.2 < n < 0.4. High speed video observation showed that the process of the TVC inception strongly depends on water quality. In the experiments, unsteady behaviors of TVC were also investigated. Strong interactions between sheet cavitation and TVC were observed.
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Viola, Ignazio Maria, and Richard G. J. Flay. "Pressure Distributions on Sails Investigated Using Three Methods: On-Water Measurements, Wind-Tunnel Measurements, and Computational Fluid Dynamics." In SNAME 20th Chesapeake Sailing Yacht Symposium. SNAME, 2011. http://dx.doi.org/10.5957/csys-2011-004.
Abstract:
The main results of a two-year project aimed at comparing full-scale tests, wind tunnel tests, and numerical analysis predictions are presented. Pressure measurements were obtained from both full-scale tests and wind-tunnel tests, in upwind and downwind conditions. The upwind wind tunnel test condition was modelled using a Vortex Lattice code, while the downwind wind-tunnel test was modelled using a Navier-Stokes code. The pressures obtained from the three different methods are compared on three horizontal sections of the headsail, mainsail, and asymmetric spinnaker. In general the pressures from the three experiments showed good agreement. In particular, very good agreement was obtained between the numerical computations and the wind tunnel test results. Conversely, the results from the downwind full-scale pressure measurements showed less similarity due to a slightly tightened trim being used for the spinnaker in the on-water tests. Full-scale tests allow the action of unsteadiness due to the wind, wave and yacht movements to affect the results. This unstable environment caused the asymmetric spinnaker to move around, and a tightened trim was required to prevent the spinnaker from collapsing.
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Vasconcelos, Jose G., and Steven J. Wright. "Surge Associated With Air Expulsion in Near-Horizontal Pipelines." In ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45265.
Abstract:
A number of situations of engineering interest are associated with the relatively rapid filling of a nearly horizontal pipeline. The displacement of the air may lead to a number of different transient conditions of concern in engineering design. Our specific application relates to the use of underground storage tunnels to mitigate combined sewage overflows. Historically, the operation of these system have created surges initiated when the tunnel passes to a surcharged condition that have resulted in “geysering” in which an air/water combination is expelled to the ground surface through manholes or other risers. Numerical models that have been created to describe the phenomena generally treat the air as a passive phase that exists at atmospheric pressure and disappears when the water fills the tunnel. In an attempt to understand the conditions leading to extreme surges, a physical model that reproduced the essential elements of the tunnel filling process was created. This model was filled at one end in a fill box in which the maximum water level was controlled with an overflow weir. A surge riser was mounted at the opposite end of the pipeline to observe the magnitudes of surges created under a number of different flows created by varying the inflow rate, the initial water level in the pipe, and the pipe slope. In general, initiation of the filling process generated a hydraulic bore that propagated through the system until the tunnel reached a surcharged state and the maximum surge generated depends on the dynamics of the bore. However, under certain flow conditions, the water level in the surge riser was observed to increase prior to the arrival of the bore, an occurrence that can only be explained by pressurization of the air in the pipe. Subsequent experiments confirmed this explanation and a modified experimental setup was created to elucidate the important effects of the air. Measurements were made of a number of key flow variables and are found to be consistent with the predictions of a numerical model that considers the elementary dynamics of the air.
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Ispir, Ali Can, Tugce Karatas, Eren Dikec, and Seyhan Onbasioglu. "Experimental Investigation of Effect of Pore Diameter on Nucleate Boiling Heat Transfer in Reentrant Tunnel Structured Surfaces." In ASME 2017 15th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icnmm2017-5533.
Abstract:
This paper focuses on experimental studies of boiling heat transfer on surfaces with reentrant tunnels and pores. Three structured surface which have same tunnel width and height but different pore diameter, have been developed for enhancement boiling heat transfer. The experimental studies were carried out for the structured surfaces using distilled water at atmospheric pressure. The narrow reentrant tunnels are parallel to each other and have 3 mm width, 4 mm height. A number of pores whose diameter 1.5 and 2.0 mm were machined on lateral surfaces of tunnels. The surfaces were termed according to their geometric specifications as 3.0W-30-30, 1.5D-3.0W-30-30, 2.0D-3.0W-30-30. D and W capitals represent pore diameter and tunnel width, respectively. 30-30 part of name shows the dimension of square surface. The tunnels were used to increase area of heat transfer and active nucleation sites of vapor bubbles. In addition, sufficient amount of liquid must be supplied and vapor bubbles should be released fast from the boiling surface before they merge on the surfaces under conditions especially with high heat fluxes. Therefore, it was considered that pore structures would help for fluid transition hence the bubble frequency will increase. Pool boiling experiments were held to determine the performance of surfaces in different range of heat fluxes. Besides, high-speed visualization studies were conducted with high speed camera to observe behavior of nucleation of vapor bubbles. Amongst different geometry sizes the surface which has 1.5 mm of pore diameter (1.5D-3.0W-30-30) demonstrated the best nucleate boiling performance at high heat fluxes. However, the pored ones without pores has higher augmentation than pored structures at low heat fluxes. Thus, it is concluded that pored structures caused active nucleation sites to decrease under low heat fluxes.
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Dropkin, Amanda M., Stephen A. Huyer, and Charles Henoch. "Combined Experimental/Numerical Development of Propulsor Evaluation Capability." In ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting collocated with 8th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-30375.
Abstract:
Propulsor design methods utilize Computational Fluid Dynamics (CFD) to develop initial propulsor configurations and predict the full-scale in-water performance of these optimal designs. However, like all numerical models, these CFD models need experimental validation to provide a sufficient level of confidence in the design. The actual data needed to validate CFD models include propulsor inflow velocities and thrust and are impractical to collect for full-scale vehicles. As a result, the in-water propulsor performance can be significantly different than CFD predictions. Another approach in the propulsor design process is to experimentally test a subscale version of the vehicle and appropriately scale results. This scaling is often unreliable due to differences between open water conditions and the flow in the laboratory facility. This paper presents a method to combine CFD modeling with subscale experiments to improve full-scale propulsor performance prediction. Laboratory experiments were conducted on subscale generic torpedo models in the 12″ × 12″ water tunnel located at the Naval Undersea Warfare Center in Newport, Rhode Island. This model included an operational ducted post-swirl propulsor. Laser Doppler Velocimetry was used to measure several velocity profiles along the torpedo hull. The experimental data were used in this project to validate the CFD models constructed using the commercial CFD software, Fluent®. Initially, axisymmetric two-dimensional simulations investigated the bare body, hull only case, and a shrouded body without the propulsor. These models were selected to understand the axisymmetric flow development and investigate methods to best match the propulsor inflow. A variety of turbulence models including the realizable k-epsilon model and the Spallart-Almaras model were investigated and ultimately the numerical and experimental velocity profiles were found to match within 3%. Based on these water tunnel simulations, differences between the flow in the facility and open water could then be characterized. These differences quantified both the effect of Reynolds number as well as local flow acceleration due to tunnel blockage effects. Full 3-D flow simulations were then conducted with an operating propulsor and compared with the corresponding subscale experimental data. Finally, simulations were conducted for full-scale tests and compared with actual in-water data. While the in-water data was limited to propulsor rpm and vehicle velocity, the operating advance ratio could be determined as well as the estimated vehicle thrust. This provided a method to utilize CFD/experiments to bridge the gap between subscale and full-scale tests. The predicted in-water advance ratio of 1.87 was very close to the measured value of 1.75.