Journal articles on the topic 'Wind tunnel startup'
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Zheng, Guoping, Dapeng Xue, Yizhou Zhuang, and Yusheng Zhu. "Study on Time Factors in the Smoke Control Process of Highway Tunnel Fires." Advances in Civil Engineering 2021 (November 30, 2021): 1–14. http://dx.doi.org/10.1155/2021/6670559.
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Fire is the most deadly risk during tunnel operation. Early rapid response and a reasonable smoke control plan are very important to evaluate tunnel fire performance. In order to study the relevant time factors for smoke management in a highway tunnel, firstly, the logical sequence and time of the fire alarm system (FAS) startup are investigated and analyzed. Then, according to the one-dimensional fluid mechanics model, the time rule of adjusting the airflow field in the tunnel from the normal operation stage to the emergency ventilation state is analyzed theoretically. Finally, the abovementioned theoretical formulas are verified through the employment of model experiments. The analysis shows that the time that passes from the start of the fire to when the exhaust fan is activated is close to 3 minutes. The time required to form a stable critical wind speed, however, is close to 7 minutes, which is longer than the 5 minutes it takes for the fire to reach its maximum temperature. Due to inertia, it takes about 0.5 to 2 minutes for the air velocity in tunnels of different lengths to drop from the traffic piston wind speed to the critical wind speed. If reverse smoke extraction is required, however, the duration is between 3 and 8 minutes. The conclusion is of guiding significance for the preparation of the emergency linkage control scheme for tunnels, as well as for the setting of initial boundary conditions for CFD fire simulations.
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Akbari, Vahid, Mohammad Naghashzadegan, Ramin Kouhikamali, Farhad Afsharpanah, and Wahiba Yaïci. "Multi-Objective Optimization of a Small Horizontal-Axis Wind Turbine Blade for Generating the Maximum Startup Torque at Low Wind Speeds." Machines 10, no. 9 (September 8, 2022): 785. http://dx.doi.org/10.3390/machines10090785.
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Generating a high startup torque is a critical factor for the application of small wind turbines in regions with low wind speed. In the present study, the blades of a small wind turbine were designed and optimized to maximize the output power and startup torque. For this purpose, the chord length and the twist angle were considered as design variables, and a multi-objective optimization study was used to assess the optimal blade geometry. The blade element momentum (BEM) technique was used to calculate the design goals and the genetic algorithm was utilized to perform the optimization. The BEM method and the optimization tools were verified with wind tunnel test results of the base turbine and Schmitz equations, respectively. The results showed that from the aerodynamic viewpoint, the blade of a small wind turbine can be divided into two sections: r/R < 0.52, which is responsible for generating the startup torque, and r/R ≥ 0.52, where most of the turbine power is generated. By increasing the chord length and twist angle (especially chord length) in the r/R < 0.52 section and following the ideal chord length and twist angle distributions in the r/R ≥ 0.52 part, a 140% rise in the startup torque of the designed blade was observed with only a 1.5% reduction in power coefficient, compared with the base blade. Thereby, the startup wind speed was reduced from 6 m/s for the base blade to 4 m/s for the designed blade, which provides greater possibilities for the operation of this turbine in areas with lower wind speeds.
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Čeheľová, Dagmara, Michal Franek, and Boris Bielek. "Atmospheric Boundary Layer Wind Tunnel of Slovak University of Technology in Bratislava." Applied Mechanics and Materials 887 (January 2019): 419–27. http://dx.doi.org/10.4028/www.scientific.net/amm.887.419.
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Aerodynamics is a relatively young scientific discipline, which started developing in the 50´s of last century. There are known several methods for calculating and measuring of the aerodynamic variables – in-situ measurements, wind tunnel measurements, CFD simulations and calculations according to national standards. Each method has its advantages and disadvantages. Nowadays a large focus is on experimental verifying the findings achieved with calculations help and CFD simulations. One of the verification possibilities are measurements in wind tunnels. The submitted paper deals with construction and using of the wind tunnel by the Slovak University of Technology in Bratislava. This device was put into operation after experimental verification in 2012, so this wind tunnel is one of the newest of its kind in Europe. The concept of the construction of individual structural elements and the wind tunnel parts has been designed in collaboration with the Aeronautical Research and Test Institute (Czech Republic) and was based on previous made analysis of aerodynamic tunnels. Its structure was designed and realized by Konštrukta Industry (Slovak Republic). We could it characterized as atmospheric boundary layer wind tunnel with open test section. It is unique with two test sections – front and back measuring space, where the front measuring space is used for uniform flow and the back measuring space is used for turbulent flow. That is why it is not only usable in the civil engineering sector (buildings, bridges, chimneys etc.), but also in city urbanism (pedestrian wind comfort and wind safety, dispersion of air pollutants), aircraft and automotive industries.
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Yamashita, Hiroshi, Naoshi Kuratani, Masahito Yonezawa, Toshihiro Ogawa, Hiroki Nagai, Keisuke Asai, and Shigeru Obayashi. "Wind Tunnel Testing on Start/Unstart Characteristics of Finite Supersonic Biplane Wing." International Journal of Aerospace Engineering 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/231434.
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This study describes the start/unstart characteristics of a finite and rectangular supersonic biplane wing. Two wing models were tested in wind tunnels with aspect ratios of 0.75 (model A) and 2.5 (model B). The models were composed of a Busemann biplane section. The tests were carried out using supersonic and transonic wind tunnels over a Mach number range of0.3≤M∞≤2.3with angles of attack of 0°, 2°, and 4°. The Schlieren system was used to observe the flow characteristics around the models. The experimental results showed that these models had start/unstart characteristics that differed from those of the Busemann biplane (two dimensional) owing to three-dimensional effects. Models A and B started at lower Mach numbers than the Busemann biplane. The characteristics also varied with aspect ratio: model A (1.3<M∞<1.5) started at a lower Mach number than model B (1.6<M∞<1.8) owing to the lower aspect ratio. Model B was located in the double solution domain for the start/unstart characteristics atM∞=1.7, and model B was in either the start or unstart state atM∞=1.7. Once the state was determined, either state was stable.
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Bai, Ling, and Ke Liu. "Research on Vortex-Induced Vibration Behavior of Steel Arch Bridge Hanger." Applied Mechanics and Materials 137 (October 2011): 429–34. http://dx.doi.org/10.4028/www.scientific.net/amm.137.429.
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A fluid-structure interaction numerical simulation technique based on CFD has been developed to study the vortex-induced vibration behavior of steel arch bridge hanger. Above all, wind acting on bridge hanger is simulated by using Flunet and then vortex-induced dynamic motion of hanger is solved by method in the User Defined Function (UDF). Finally hanger’s transient vibration in wind is achieved by dynamic mesh method provided by Fluent. Using this technique, the vortex-induced vibration behavior of hanger of the Nanjing Dashengguan Yangtze River Bridge is analyzed, including vibration amplitude, vibration-started wind speed and vortex shedding frequency. The study also considers influences of different section type (rectangle, chamfered rectangle and H) of hanger. The following conclusions are obtained. Firstly hanger of different section has different vibration behavior. Secondly vibration-started wind speed of different section hanger differs with each other. Thirdly relation between vibration amplitude and incoming wind speed varies obviously. At the same time, numerical results are compared with those of one wind tunnel test and the out coming is satisfied. Relation between vibration amplitude and wind speed in both numerical simulation and wind tunnel test is similar because vibration-started wind speed in numerical result has only 10% discrepancy with that in wind tunnel test while vibration amplitude’s discrepancy is only 15%. Consequently, analysis results show the reliability of this numerical simulation technique.
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Logunov, Boris A., and Ilya A. Kharin. "Improving the Efficiency of Testing Aircraft Models for Flutter Using Measurement and Information Systems in a Subsonic Wind Tunnel." Vestnik MEI, no. 5 (2021): 103–7. http://dx.doi.org/10.24160/1993-6982-2021-5-103-107.
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The technology of testing dynamically and structurally similar aircraft models for flutter in subsonic wind tunnels using information and measurement systems (IMS) is based on collection and processing of experimental data obtained in subcritical modes. The data received feature a significant scatter, in view of which the critical flutter speed is determined with acceptable accuracy only after its statistical post-processing. In view of the need to study a number of model versions during the flutter tests, the technology involved significant time spent for wind tunnel air flow startups and for processing of experimental data. To decrease the above-mentioned time expenditures, a more efficient technology was developed, using which it becomes possible, owing to a more sophisticated IMS structure, to quickly determine the critical flutter speed with acceptable accuracy directly in the course of tests. The essence of the new technology is that it eliminates interference that occurs in the existing system by introducing data transmission equipment into the IMS structure via a wireless Wi-Fi network. In view of this feature, it becomes possible to do the following in the course of testing the model for flutter in subcritical modes: to record the model time response to the impulse force, perform its spectral analysis, and plot the amplitude spectrum. The plotted amplitude spectrum is then used to measure the fundamental harmonic component, calculate and plot the functional dependence of the quantity inverse to the amplitude of the model oscillations fundamental tone on the flow velocity using approximation and extrapolation methods. The critical flutter speed is determined with acceptable accuracy when the functional dependence graph crosses zero. It is shown that the use of the proposed technology in flutter tests makes it possible to shorten the time taken to start the wind tunnel by a factor of 5 and the time taken to process the experimental data by a factor of 6, with the resulting error not exceeding 5%. It is recommended to use the technology in the Central Aerohydrodynamic Institute's subsonic wind tunnels in performing aircraft models flutter tests.
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Wiriadidjaja, Surjatin, Azmin Shakrine Mohd Rafie, Faizal Mustapha, Fadilah Hasim, Tabrej Khan, and Harijono Djojodihardjo. "Basic Geometries of the New Closed Circuit Wind Tunnel of the Universiti Putra Malaysia (UPM)." Applied Mechanics and Materials 629 (October 2014): 376–81. http://dx.doi.org/10.4028/www.scientific.net/amm.629.376.
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The existing UPM low speed wind tunnel was usually occupied by students, who carried out their final year projects or postgraduate researches, so that there was hardly free time slot for any additional testing work. Due to this reason, a new wind tunnel project has been started recently. Some basic specifications of the new tunnel have been pre-selected before the project was started, which comprised the following design decisions: a tunnel speed of 50 m/s, a test section area of 1´1 m2, and a closed circuit tunnel type. It wouldn’t be difficult to perceive that this pre-selection was made based on some of the trade-off results among the project’s options and constraints. This paper is aimed to present a simple analysis on the design of the new tunnel, focusing only on its basic geometries. Some design decisions that have been made related to its basic geometries are analyzed and reported in this paper. This analysis may be considered as a design verification of the new tunnel or even perhaps be regarded as scientific justification for its existence.
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Hong, B. G., B. R. Kang, J. C. Choi, and P. Y. Oh. "Characteristics of a plasma wind tunnel for the development of thermal protection materials." Aeronautical Journal 121, no. 1240 (May 30, 2017): 821–34. http://dx.doi.org/10.1017/aer.2017.35.
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ABSTRACTThermal plasma wind tunnels with power of 0.4 MW and 2.4 MW have been constructed at Chonbuk National University (CBNU) in Korea. This facility is capable of producing a heat flux greater than 10 MW/m2, a level that is relevant for testing thermal protection materials that are used for re-entry vehicles in space transportation. A segmented arc plasma torch was adopted as a plasma source; this was designed to have high thermal efficiency and long life, and to produce a supersonic plasma flow with enthalpy greater than 10 MJ/kg. We investigated the characteristics of the supersonic plasma flow using intrusive and non-intrusive diagnostic systems. Ablation characteristics of potential thermal protection materials such as carbon/carbon composites and graphite were investigated with the plasma wind tunnel. Cracks and pores in the materials accelerated the erosion. For carbon/carbon composites, the pores grew and the cracks which occurred at the interfaces between the carbon fibres and the matrix propagated, while for the graphite, the erosion started at the pores and peeled off the surface.
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Suryanarayana, G. K., and S. R. Bhoi. "Prediction of total pressure characteristics in the settling chamber of a supersonic blowdown wind tunnel." Aeronautical Journal 115, no. 1171 (September 2011): 557–66. http://dx.doi.org/10.1017/s0001924000006199.
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Abstract Occurrence of transient starting and stopping loads during tests at high Mach numbers is one of the major problems in intermittent blowdown wind tunnels. It is believed that in order to overcome this problem, the wind tunnel could be started at a low Mach number and low stagnation pressure; the desired high Mach number condition could be reached by continuously changing the nozzle contour while synchronously increasing the stagnation pressure. After completing the tests, the nozzle could be brought back to the initial low Mach number accompanied by synchronous decrease in the stagnation pressure. In such a scenario, it is important to ensure that the pressure regulating valve (PRV) of the wind tunnel delivers and maintains a specified minimum stagnation pressure at any Mach number, so that supersonic breakdown of the test section flow does not occur. In this paper, the problem is formulated based on quasi-steady one-dimensional isentropic equations and numerically solved to predict the time histories of settling chamber pressure and storage tank pressure for a given trajectory of the opening of the PRV, as the Mach number is changed from Mach 1 to 4·0 continuously in four seconds and vice versa. The effects of rate of change of PRV open area and rate of change of Mach number on the stagnation pressure characteristics in the settling chamber and storage tank are predicted. The measured trajectories of the PRV in experiments in the NAL 0·6m transonic wind tunnel are used as input to the prediction program to validate the methodology. Predictions indicate that when the nozzle throat is changed from Mach 1 to 4 in four seconds, the settling chamber stagnation pressure rapidly builds up and approaches the pressure in the storage tank. Predictions show an alarming rise in free stream dynamic pressure during transition from Mach 1 to 4 and vice versa, which needs to be verified through measurements.
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Truong, Takara E., Nathaniel G. Luttmer, Ebsa R. Eshete, Alia B. M. Zaki, Derek D. Greer, Tren J. Hirschi, Benjamin R. Stewart, Cherry A. Gregory, and Mark A. Minor. "Evaluating the Effect of Multi-Sensory Stimulation on Startle Response Using the Virtual Reality Locomotion Interface MS.TPAWT." Virtual Worlds 1, no. 1 (September 9, 2022): 62–81. http://dx.doi.org/10.3390/virtualworlds1010005.
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The purpose of the study was to understand how various aspects of virtual reality and extended reality, specifically, environmental displays (e.g., wind, heat, smell, and moisture), audio, and graphics, can be exploited to cause a good startle, or to prevent them. The TreadPort Active Wind Tunnel (TPAWT) was modified to include several haptic environmental displays: heat, wind, olfactory, and mist, resulting in the Multi-Sensory TreadPort Active Wind Tunnel (MS.TPAWT). In total, 120 participants played a VR game that contained three startling situations. Audio and environmental effects were varied in a two-way analysis of variance (ANOVA) study. Muscle activity levels of their orbicularis oculi, sternocleidomastoid, and trapezius were measured using electromyography (EMG). Participants then answered surveys on their perceived levels of startle for each situation. We show that adjusting audio and environmental levels can alter participants physiological and psychological response to the virtual world. Notably, audio is key for eliciting stronger responses and perceptions of the startling experiences, but environmental displays can be used to either amplify those responses or to diminish them. The results also highlight that traditional eye muscle response measurements of startles may not be valid for measuring startle responses to strong environmental displays, suggesting that alternate muscle groups should be used. The study’s implications, in practice, will allow designers to control the participants response by adjusting these settings.
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Feng, Fang, Guoqiang Tong, Yunfei Ma, and Yan Li. "Numerical Simulation and Wind Tunnel Investigation on Static Characteristics of VAWT Rotor Starter with Lift-Drag Combined Structure." Energies 14, no. 19 (September 27, 2021): 6167. http://dx.doi.org/10.3390/en14196167.
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In order to get rid of the impact of the global financial crisis and actively respond to global climate change, it has become a common choice for global economic development to develop clean energy such as wind energy, improve energy efficiency and reduce greenhouse gas emissions. With the advantages of simple structure, unnecessary facing the wind direction, and unique appearance, the vertical axis wind turbine (VAWT) attracts extensive attention in the field of small and medium wind turbines. The lift-type VAWT exhibits outstanding aerodynamic characteristics at a high tip speed ratio, while the starting characteristics are generally undesirable at a low wind speed; thus, how to improve the starting characteristics of the lift-type VAWT has always been an important issue. In this paper, a lift-drag combined starter (LDCS) suitable for lift-type VAWT was proposed to optimize the starting characteristics of lift-type VAWT. With semi-elliptical drag blades and lift blades equipped on the middle and rear part outside the starter, the structure is characterized by lift-drag combination, weakening the adverse effect of the starter with semi-elliptical drag blades alone on the output performance of the original lift-type VAWT and improving the characteristics of the lift-drag combined VAWT. The static characteristic is one of the important starting characteristics of the wind turbine. The rapid development of computational fluid dynamics has laid a solid material foundation for VAWT. Thus the static characteristics of the LDCS with different numbers of blades were investigated by conducting numerical simulation and wind tunnel tests. The results demonstrated that the static torque coefficient of LDCS increased significantly with the increased incoming wind speed. The average value of the static torque coefficient also increased significantly. This study can provide guidelines for the research of lift-drag combined wind turbines.
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Ahlefeldt, Thomas, Stefan Haxter, Carsten Spehr, Daniel Ernst, and Tobias Kleindienst. "Road to Acquisition: Preparing a MEMS Microphone Array for Measurement of Fuselage Surface Pressure Fluctuations." Micromachines 12, no. 8 (August 14, 2021): 961. http://dx.doi.org/10.3390/mi12080961.
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Preparing and pre-testing experimental setups for flight tests is a lengthy but necessary task. One part of this preparation is comparing newly available measurement technology with proven setups. In our case, we wanted to compare acoustic Micro-Electro-Mechanical Systems (MEMS) to large and proven surface-mounted condenser microphones. The task started with the comparison of spectra in low-speed wind tunnel environments. After successful completion, the challenge was increased to similar comparisons in a transonic wind tunnel. The final goal of performing in-flight measurements on the outside fuselage of a twin-engine turboprop aircraft was eventually achieved using a slim array of 45 MEMS microphones with additional large microphones installed on the same carrier to drawn on for comparison. Finally, the array arrangement of MEMS microphones allowed for a complex study of fuselage surface pressure fluctuations in the wavenumber domain. The study indicates that MEMS microphones are an inexpensive alternative to conventional microphones with increased potential for spatially high-resolved measurements even at challenging experimental conditions during flight tests.
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Bieler, Heribert. "Active flow control concepts and application opportunities." Aircraft Engineering and Aerospace Technology 89, no. 5 (September 4, 2017): 725–29. http://dx.doi.org/10.1108/aeat-01-2017-0015.
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Purpose Aerodynamics drives the aircraft performance and, thus, influences fuel consumption and environmental compatibility. Further, optimization of aerodynamic shapes is an ongoing design activity in industrial offices; this will lead to incremental improvements. More significant step changes in performance are not expected from pure passive shape design. However, active flow control is a key technology, which has the potential to realize a drastic step change in performance. Flow control targets two major goals: low speed performance enhancements mainly for start and landing phase via control of separation and drag reduction at high speed conditions via skin friction and shock wave control. Design/methodology/approach This paper highlights flow control concepts and Airbus involvements for both items. To mature flow control systematically, local applications of separation control technology are of major importance for Airbus. In parallel, but at lower maturity level, investigations are ongoing to reduce the turbulent skin friction at cruise. A popular concept to delay separation at low speed conditions is the implementation of jet actuation control systems flush mounted to the wall of aerodynamic components. Findings In 2006, DLR (in collaboration with universities Berlin, Braunschweig and industrial partner Airbus) started to study active flow control for separation delay towards application. Based on basic proof of concepts (achieved in national projects), further flow control hardware developments and wind tunnel and lab testing took place in European funded projects. Originality/value Significant lift enhancements were realized via flow control applied to the wing leading edge and the flap.
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Amri, Siti Belinda, and La Ode Abdul Syukur. "ANALISIS ALIRAN ANGIN PADA ATAP MIRING MELALUI UJI SIMULASI FLOW DESIGN." LANGKAU BETANG: JURNAL ARSITEKTUR 4, no. 2 (December 28, 2017): 136. http://dx.doi.org/10.26418/lantang.v4i2.23252.
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Bidang penelitian tentang aliran angin pada bangunan sangat penting baik untuk perencanaan bangunan maupun pemukiman. Aliran angin yang mempengaruhi bangunan memiliki dampak pada ketahanan struktural terhadap angin. Penelitian dilakukan untuk mengetahui nilai drag coefficient atau gaya hambat terhadap angin yang dihasilkan pada atap miring dengan nilai sudut yang berbeda. Metode yang digunakan adalah dengan menguji model atap melalui simulasi CFD (Computational Fluid Dynamic) pada software Autodesk Flow Design. Hasil uji lima atap miring dengan nilai 0o, 15o, 30o, 45o, dan 60o menujukkan bahwa semakin besar sudut atap maka semakin besar luas bidang atap yang bersentuhan dengan aliran angin datang, hal ini sejalan dengan nilai average drag coefficient yang dihasilkan. Atap dengan sudut 60o memiliki luas bidang atap dan nilai average drag coefficient yang tertinggi diantara kelima sudut atap yang diuji, dengan nilai luas 72 m2 menghasilkan nilai average drag coefficient sebesar 1,4. Bangunan dengan nilai drag coefficient yang tinggi memiliki resiko kerusakan struktur yang tinggi akibat angin karena memiliki bentuk yang kurang aerodinamis.Kata-kata Kunci: aliran angin, atap miring, Flow Design, drag coefficient.ANALYSIS OF WIND FLOW PATTERN ON SLOPED ROOF USING FLOW DESIGN SIMULATIONThe field of research on wind flow on buildings is important for both building planning and planning a residential areas. Wind flow affecting the building has an impact on structural resistance to the wind. The study was conducted to find out the value of drag coefficient or drag force against the wind generated on the sloped roof with different angle values. The method applied by tested the roof model through CFD (Computational Fluid Dynamic) simulation through Autodesk Flow Design software. The test results of five sloped roofs with angle 0o, 15o, 30o, 45o, and 60o showed that the higher the angle of the roof, the larger the area of the roof in contact with the approaching wind flow. This is in line with the average drag coefficient value generated. The roof with an angle of 60o has a large roof area and the highest average drag coefficient among the five tested roof angles, with an area of 72 m2 yields and average drag coefficient of 1.4. Buildings with high drag coefficient value have a high risk of structural damage due to wind because it has a less aerodynamic shape.Keywords: wind flow, sloped roof, Flow Design, drag coefficient REFERENCESAutodeks Help (2015), Get Started With Autodesk Flow Design, https://www.autodesk.com/products/flow-design/overview (diakses tanggal 5 November 2017)Bhandari NM, Krishna P. (2011) An Explanatory handbook on proposed IS- 875 (Part 3): Wind loads on buildings and structure. IITK-GSDMA Project on Building Codes.Boutet, T. (1987). Controlling Air Movement. New York: McGraw Hill.Chung, TJ., (2010), Computational Fluid Dynamic. Cambridge: Cambidge University Press.Driss, S., Driss, Z., & Kammoun, I. K. (2014). Impact of Shape of Obstacle Roof on the Turbulent Flow in a Wind Tunnel. American Journal of Energy Research, 90-98.Groat, Linda N., David Wang (2002), Architectural Research Methods, New York: John Wiley and Sons.Guirguis, N., El-Aziz, A. A., & Nassief, M. (2007). Study of wind effects on different buildings of pitched roofs. Desalination, 190–198.Lechner, N. (2007). Heating, Cooling, Lighting: Metode Desain untuk Arsitektur. Jakarta: Rajawali.Lippsmeier, G. (1997). Bangunan Tropis. Jakarta: Erlangga.Mujiasih, S., & Primadi S.T., (2014), Analisis Kejadian Puting Beliung Tanggal 11 Desember 2013 di Wilayah Denpasar Bagian Selatan–Bali, Prosiding Workhop Operasional Radar dan Satelit Cuaca, Jakarta: BMKG.Stathopoulos and B.A. Baskaran, (1996) “Computer simulation of wind environmental conditions around buildings”, Engineering Structures, 18(11), 876-885.Szokolay, N. V. (1980). Environmental Science Handbook. New York: Wiley.Tominaga, Y., Akabayashi, S., Kitahara, T., & Arinami, Y. (2015). Air flow around isolated gable-roof building with different roof pitches: Wind Tunnel experiments and CFD Simulation. Building and Environment, 204-213.
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Eckerle, W. A., and L. S. Langston. "Horseshoe Vortex Formation Around a Cylinder." Journal of Turbomachinery 109, no. 2 (April 1, 1987): 278–85. http://dx.doi.org/10.1115/1.3262098.
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An experimental investigation was conducted to characterize a symmetric horseshoe vortex system in front of and around a single large-diameter right cylinder centered between the sidewalls of a wind tunnel. Surface flow visualization and surface static pressure measurements as well as extensive mean velocity and pressure measurements in and around the vortex system were acquired. The results lend new insight into the formation and development of the vortex system. Contrary to what has been assumed previously, a strong vortex was not identified in the streamwise plane of symmetry, but started a significant angular distance away from it. Rather than the multiple vortex systems reported by others, only a single primary vortex and saddle point were found. The scale of the separation process at the saddle point was much smaller than the scale of the approaching boundary layer thickness. Results of the present study not only shed light on such phenomena as the asymmetric endwall flow in axial turbomachinery but can also be used as a test case for three-dimensional computational fluid mechanics computer codes.
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Ramzi, Nur Ain Shafiza, Kee Quen Lee, NUR AMIRA BALQIS MOHD ZAINURI, HOOI SIANG KANG, NOR’AZIZI OTHMAN, and KENG YINN WONG. "FLOW INDUCED VIBRATION IN SQUARE CYLINDER OF VARIOUS ANGLES OF ATTACK." IIUM Engineering Journal 23, no. 1 (January 4, 2022): 358–69. http://dx.doi.org/10.31436/iiumej.v23i1.1804.
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An experimental study was carried out to identify the effect of angle of attack on flow-induced vibration (FIV) of square cylinders. The experiment was conducted at the Aeronautical and Wind Engineering Laboratory (AEROLAB), UTM Kuala Lumpur using a wind tunnel that was free from external wind conditions. A supporting structure was designed and fabricated to conduct this experiment. The importance of this support structure was to enable the rigid cylinder to suspend and vibrate freely upon excitation of wind speed. The results were analysed through the response of amplitude and frequency of the rigid cylinder over a velocity range of 0.5m/s to 4.0m/s. The results showed that for a square cylinder of ?=0°, vortex-induced vibration (VIV) occurred at low reduced velocity (UR) in range of 5 ? UR ? 10 and galloping occurred at higher reduced velocity which started at UR=15. A tranquil zone was found between VIV and galloping in the reduced velocity range of 10 ? UR ? 15. As for ?=22.5° and 45°, only VIV response was found at low reduced velocity in range of 4? UR ? 9. ABSTRAK: Satu kajian eksperimentasi telah dilakukan bagi mengenal pasti pengaruh sudut serangan oleh getaran cetusan-aliran (FIV) dalam silinder persegi. Eksperimen ini dijalankan di Makmal Kejuruteraan Aeronautika dan Angin (AEROLAB), UTM Kuala Lumpur dengan menggunakan terowong angin yang bebas dari pengaruh angin luar. Struktur sokongan telah direka dan difabrikasi bagi tujuan eksperimen ini. Ini penting bagi membolehkan silinder pegun tergantung dan bergetar dengan bebas semasa ujian kelajuan angin. Dapatan kajian dianalisis melalui tindak balas amplitud dan frekuensi silinder pegun pada kadar halaju 0.5m/s sehingga 4.0m/s. Hasil kajian menunjukkan bahawa bagi silinder persegi ? = 0 °, getaran pengaruh-vorteks (VIV) berlaku pada halaju rendah (UR) dalam julat 5 ? UR ? 10 dan getaran lebih teruk telah ketara berlaku pada kadar halaju berkurang iaitu bermula pada UR = 15. Zon tenang dijumpai antara VIV dan getaran teruk pada kadar halaju berkurang 10 ? UR ? 15. Adapun pada ? = 22.5° dan 45°, hanya tindak balas VIV dijumpai pada halaju rendah dalam kadar 4? UR ? 9.
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Schultze-Motel, P., and I. Lamprecht. "CORRELATION OF SOUND GENERATION AND METABOLIC HEAT FLUX IN THE BUMBLEBEE BOMBUS LAPIDARIUS." Journal of Experimental Biology 187, no. 1 (February 1, 1994): 315–18. http://dx.doi.org/10.1242/jeb.187.1.315.
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Flying insects produce extreme amounts of heat as a by-product during the contractions of their thoracic flight muscles (Heinrich, 1989). Before flight, metabolic heat may serve to warm up the thoracic muscles until the minimum lift-off temperature is reached (Heinrich, 1974b; Stone and Willmer, 1989; Esch and Goller, 1991). Social bees and wasps are also able to use the heat produced in their flight muscles for brood incubation and for active regulation of nest temperatures (Heinrich, 1974a; Seeley and Heinrich, 1981; Schultze-Motel, 1991). In this study, we report simultaneous measurements of heat flux and sound generation by wing buzzing in individual bumblebee workers (Bombus lapidarius L.). Bumblebees used in the experiments were taken from colonies in observation nest boxes (Schultze-Motel, 1991) and placed into the cylindrical 100 ml stainless-steel vessel of a Calvet-type microcalorimeter (MS 70, Setaram, Lyon; Wadso, 1987). A small microphone had been installed below the screw cap of the calorimeter vessel. The sensitivity of the calorimeter under these conditions was 41.7 mV W-1. Both the calorimeter and the microphone signals were amplified and recorded on a dual-channel chart recorder. In 32 out of a total of 36 measurements, the bumblebees showed prolonged periods of sound generation, most frequently at the beginning of experiments. We assume that the sound was not produced in an alarm reaction, but by flight movements of the wings when the animals attempted to lift off inside the calorimeter vessel. The buzzing sounds produced by bumblebees are caused by oscillations of the flight muscles inside the metathorax (Schneider, 1975). Previous endoscopic observations of bumblebees sitting on the bottom of our calorimeter vessel had shown that there was a one-to-one correlation between episodes of wing movements and sound production. The microphone recordings thus allowed an easy way of measuring locomotor activity inside the calorimeter. The simultaneous recordings of calorimeter and microphone signals showed a very good agreement between periods of sound generation and increased metabolic heat flux from the animals. This was most conspicuous in some experiments without continuous wing buzzing activity but with distinct episodes of intense sound generation that were always coupled to a simultaneous increase of heat flux (Fig. 1). Between episodes of sound generation, heat flux typically returned from maxima exceeding 200 W kg-1 to basal values around 10 W kg-1. During one experiment, we recorded a deviation from the usually observed synchronism between metabolic heat flux and sound generation (Fig. 2). The acoustic activity of the animal started about 45 min after the beginning of the experiment. Remarkably, the heat flux signal showed a steep increase as early as 5 min before the first sound generation was observed. During the period of continuous wing buzzing, heat fluxes of more than 350 W kg-1 were measured. These fluxes correspond to metabolic rates during free flight in other Hymenoptera: about 300 W kg-1 in the carpenter bee Xylocopa capitata (Nicolson and Louw, 1982), 300-500 W kg-1 in honeybees, Apis mellifera (Nachtigall et al. 1989) and about 350 W kg-1 in the bumblebees Bombus lucorum and B. pascuorum flying in a wind tunnel (Ellington et al. 1990). We suggest that the sharp increase in heat flux before the beginning of sound generation represents a preflight endothermic warm-up event. Apparently, the warm-up of flight muscles proceeded without any wing buzzing.
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Ravichandran, Manickam, Tew Hui Xian, Guruswamy Prabhakaran, Subramani Parasuraman, and Mohd Nor Norazmi. "Live, Genetically Attenuated, Cold-Chain-Free Cholera Vaccine—A Research and Development Journey: Light at the End of a Long Tunnel." Malaysian Journal of Medical Sciences 29, no. 2 (April 21, 2022): 1–7. http://dx.doi.org/10.21315/mjms2022.29.2.1.
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Cholera, a diarrheal disease caused by Vibrio cholerae (V. cholerae) O139 and O1 strains, remains a public health problem. The existing World Health Organization (WHO)- licenced, killed, multiple-dose oral cholera vaccines demand ‘cold-chain supply’ at 2 °C–8 °C. Therefore, a live, single-dose, cold-chain-free vaccine would relieve significant bottlenecks and costs of cholera vaccination campaigns. Our cholera vaccine development journey started in 2000 at Universiti Sains Malaysia with isolation of the hemA gene from V. cholerae, followed by development of a gene mutant vaccine candidate VCUSM2 against V. cholerae O139 in 2006. In 2010, VCUSM2 reactogenicity was reduced by replacing its two wild-type ctxA gene copies with mutated ctxA to produce strain VCUSM14. Introducing the hemA gene into VCUSM14 created VCUSM14P, a strain with the 5- aminolaevulinic acid (ALA) prototrophic trait and excellent colonisation and immunological properties (100% protection to wild-type challenged rabbits). It was further refined in Asian Institute of Medicine, Science and Technology (AIMST University), with completion of single- and repeated-dose toxicity evaluations in 2019 in Sprague Dawley (SD) rats, followed by development of a novel cold-chain-free VCUSM14P formulation in 2020. VCUSM14P is unique for its intact cholera toxin B, a known mucosal adjuvant. The built-in adjuvant makes VCUSM14P an ideal vaccine delivery platform for emerging diseases (e.g. severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2] and tuberculosis). Our vaccine formulation mimics natural infection, remains non-reactogenic and immunogenic in vivo, and protects against infection and disease. It will also cost less and be less cumbersome to distribute due to its stability at room temperature. These features could revolutionise the outreach of this and other vaccines to meet global immunisation programmes, particularly in low-resourced areas. The next stage of our journey will be meeting the requisite regulatory requirements to produce the vaccine for rollout to countries where it is most needed.
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S.P., Setyo Hariyadi, Setiyo Setiyo, and Supriadi Supriadi. "Separasi dan Reattachment Aliran di Belakang Gundukan (Bump) Setengah Lingkaran, Segitiga dan Persegi Panjang." Jurnal Penelitian 2, no. 4 (December 4, 2017): 254–60. http://dx.doi.org/10.46491/jp.v2e4.60.254-260.
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Characteristic of viscous flow through a contour always become the interesting topic to be studied. This research studied characteristic of turbulent viscous flow through a flat plate mounted by bump. Target of this research is to know the flow characteristic through the semicircle, triangle and quadrangular bump, and also to get distribution coefficient of pressure (Cp), separation point, coefficient of pressure drag (CDp) and coefficient of total drag (CD). Beside that, in this research also conduct smoke visualization to know visualization of turbulent viscous flow through a flat plate mounted by bump. This experiment is conducted in subsonic wind tunnel. Form of the bump that is used are semicircle, triangle and quadrangular, and free stream velocity equal to 9.75 m/s and 15.5 m/s. Pressure coefficient got from static pressure measurement over flat plate and bump by using wall pressure tap. Coefficient of pressure drag (CDp) got from calculation based pressure. The measurement of velocity profile over flat plate and bump by using pitot tube. Measurement conducted at 6 point before side of upstream bump, 1 point at top bump and 13 point after side of downstream bump where distance between the points are 20 mm. While for the direction of vertical, the measurement taken at 80 point started from height 80 mm from surface until near the surface. Existence of bump on flat plate result the flow becomes separation so that generate the total drag force addition over flat plate. The highest total drag force occured on flat plate with triangle bump, then on flat plate with quadrangular bump and the smallest occur on flat plate with semicircle bump.
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Vassal, G., N. Hamelin, P. Opolon, R. Versace, and B. Geoerger. "The topoisomerase I inhibitor gimatecan exhibits anti-tumor activity against malignant glioma xenografts as single agent and in combination." Journal of Clinical Oncology 25, no. 18_suppl (June 20, 2007): 2081. http://dx.doi.org/10.1200/jco.2007.25.18_suppl.2081.
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2081 Background: Gimatecan, a novel oral lipohilic camptotecan (ST1481; NVP-LBQ707), has shown to irinotecan and topotecan superior anti-tumor activity against several cell lines and human xenografts. We evaluated gimatecan in microemulsion in vivo alone and in combination with temozolomide and the EGFR and VEGF tyrosine kinase inhibitor AEE788 against subcutaneous malignant glioma xenografts derived from primary tumors. Results: Gimatecan exhibited dose-dependent activity against all three advanced tumor stage glioma models with IGRG93 being the most sensitive: 0.10 to 0.25 mg/kg gimatecan daily orally in a protracted schedule 5 days/week during 4 weeks resulted in 100% partial and complete tumor regressions, significant tumor growth delays (TGD; 48 to >100 days), log cell kills of 4.3 to 9.1, and were thus considered as ++++ highly active according to the SRI activity criteria. Anti-tumor activity in the TP53 wild-type IGRG93 correlated with significant induction of apoptotic cell death, as measured by TUNEL and cell cycle analysis, and lack of induction of p21. Moreover, combination of gimatecan and temozolomide resulted in synergistic activity against the TP53 wild-type IGRG121 glioblastoma and gimatecan at the MTD could be combined with temozolomide without enhanced toxicity. Gimatecan 0.19 mg/kg q5/wx4w combined with AEE788 50 mg/kg q3/wx4w was evaluated against the TP53 mutant, EGFR gene amplified IGRG88 glioma. Both agents were highly active resulting in 100% tumor regression. Gimatecan treated tumors started to grow 2–3 weeks after treatment end, while tumors treated with AEE788 regrew directly after treatment stop resulting in less significant TGD. Gimatecan and AEE788 given simultaneously during 4 weeks yielded less significant TGD compared to gimatecan alone, thus antagonistic effects. AEE788 induced G1 cell growth arrest which may reduce sensitivity to gimatecan, necessitating S-phase to be most efficient. An alternative schedule with gimatecan followed by AEE788 may be more appropriate. Conclusions: Gimatecan is highly active against malignant glioma xenografts and has synergistic activity with temozolomide suggesting this new topoisomerase I inhibitor for the treatment of malignant glioma. No significant financial relationships to disclose.
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Holst, D., G. Pechlivanoglou, F. Wegner, C. N. Nayeri, and C. O. Paschereit. "Potential of Retrofit Passive Flow Control for Small Horizontal Axis Wind Turbines." Journal of Engineering for Gas Turbines and Power 139, no. 3 (October 11, 2016). http://dx.doi.org/10.1115/1.4034543.
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The present paper analyzes the effect of passive flow control (PFC) with respect to the retrofitting on small horizontal axis wind turbines (sHAWTs). We conducted extensive wind tunnel studies on a high performance low Reynolds airfoil using different PFC elements, i.e., vortex generators (VGs) and Gurney flaps (GF). qblade, an open source blade element momentum (BEM) code, is used to study the retrofitting potential of a simulated small wind turbine. The turbine design is presented and discussed. The simulations include the data and polars gained from the experiments and give further insight into the effects of PFC on sHAWTs. Therefore, several different blades were simulated using several variations of VG positions. This paper discusses their influence on the turbine performance. The authors especially focus on the startup performance as well as achieving increased power output at lower wind speeds. The vortex generators reduce the risk of laminar separation and enhance the lift in some configurations by more than 40% at low Reynolds numbers.
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Bianchini, Alessandro, Francesco Balduzzi, John M. Rainbird, Joaquim Peiro, J. Michael R. Graham, Giovanni Ferrara, and Lorenzo Ferrari. "An Experimental and Numerical Assessment of Airfoil Polars for Use in Darrieus Wind Turbines—Part II: Post-stall Data Extrapolation Methods." Journal of Engineering for Gas Turbines and Power 138, no. 3 (September 22, 2015). http://dx.doi.org/10.1115/1.4031270.
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Accurate post-stall airfoil data extending to a full range of incidences between −180 deg and +180 deg are important to the analysis of Darrieus vertical-axis wind turbines (VAWTs), since the blades experience a wide range of angles of attack, particularly at the low tip-speed ratios (TSRs) encountered during startup. Due to the scarcity of existing data extending much past stall and the difficulties associated with obtaining post-stall data by experimental or numerical means, wide use is made of simple models of post-stall lift and drag coefficients in wind turbine modeling (through, for example, blade element momentum (BEM) codes). Most of these models assume post-stall performance to be virtually independent of profile shape. In this study, wind tunnel tests were carried out on a standard NACA 0018 airfoil and a NACA 0018 conformally transformed to mimic the “virtual camber” effect imparted on a blade in a VAWT with a chord-to-radius ratio c/R of 0.25. Unsteady computational fluid dynamics (CFD) results were taken for the same airfoils both at stationary angles of attack and at angles of attack resulting from a slow VAWT-like motion in an oncoming flow, the latter to better replicate the transient conditions experienced by VAWT blades. Excellent agreement was obtained between the wind tunnel tests and the CFD computations for both the symmetrical and cambered airfoils. Results for both airfoils also compare favorably to earlier studies of similar profiles. Finally, the suitability of different models for post-stall airfoil performance extrapolation, including those of Viterna–Corrigan, Montgomerie, and Kirke, was analyzed and discussed.
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Van Treuren, Kenneth W. "Current Status and Future Challenges for Small Horizontal Axis Wind Turbines." Journal of Engineering for Gas Turbines and Power 141, no. 9 (August 30, 2019). http://dx.doi.org/10.1115/1.4044382.
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Abstract This paper examines the category of small wind turbines. Numerous definitions are found in the literature. However, this paper's focus is on fixed pitch, small horizontal axis wind turbines, with a direct drive DC generator in the 1–10 kW class. Small wind turbine growth world-wide is analyzed for trends and predicted development. It is necessary to discuss design tools available for design, including computational fluid dynamic models and experimentally testing both open rotors and wind tunnel models. Wind turbines must be optimized for peak performance to include startup/cut-in speeds and other modifications. These wind turbines will rely on new and purposely designed airfoils; however, for low-Reynolds number conditions, computational tools do not accurately predict separation. An analysis of noise generation as well as design techniques for reducing noise is necessary for future designs. Discussions on the technologies particular to small wind turbines should include the topics of aerodynamics and structures/materials. Small wind turbines are contributing to the concept of distributed generation. Urban applications are leading to studies of flow fields in and around buildings. Interest in hybrid systems, which combine wind with other energy generation systems such as solar, internal combustion engines, and diesel engines, is growing. These systems are advantageous for the homeowner, small business, cell phone towers, remote locations, and backup emergency power systems (to include lighting). Finally, the concept of energy storage must be addressed in the context of small wind turbines, especially those turbines used in an isolated application.
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Hammond, Charles E. "Higher Harmonic Control: A Historical Perspective." Journal of the American Helicopter Society, 2021. http://dx.doi.org/10.4050/jahs.66.022001.
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Higher harmonic control (HHC) is an approach for achieving reduced helicopter vibration by controlling the vibratory rotor airloads in such a way that the fuselage excitation is minimized. This paper is a historical look at how a program aimed at helicopter vibration reduction started as an outgrowth of fixed wing flutter suppression at NASA Langley Research Center, proved the HHC concept on aeroelastically scaled wind tunnel models and went on to demonstrate viability in full-scale flight testing on the OH-6A helicopter in 1982. Following the OH-6A flight tests, the helicopter research community was stimulated to prove the effectiveness of HHC on different configurations through analysis, wind tunnel tests, and flight tests. All of these investigations have shown HHC to be effective in reducing vibration to levels not attainable with conventional vibration control methods and without any detrimental side effects. HHC development has progressed to the point that the technology provides one more option to address the ever-present vibration problem in helicopters. The literature demonstrates that helicopter ride quality equivalent to that of fixed wing aircraft is attainable with application of HHC.
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GÖKDEMİR, Mert, Satılmış ÜRGÜN, and Sinan FİDAN. "Comparative analysis and manufacturing of airfoil structures suitable for use at low speeds." Journal of Advanced Research in Natural and Applied Sciences, June 22, 2022. http://dx.doi.org/10.28979/jarnas.1069147.
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An aerodynamic technique for calculating lift and drag coefficients is one of the required instruments in the wing design process. In recent decades, several tools and software have been developed based on aerodynamics and numerical methods. Today, aircraft architecture needs a great deal of calculation. To prevent expensive model testing, modern technologists use numerous simulation techniques. The present work explains how wing profiles can be modelled using ANSYS Fluent and tested by low velocity testing in the light of experimental literature results. With the chosen wing profile, the geometries formed in two dimensions and designed in 3 dimensions. As the method of study of the wing profiles, computational fluid dynamics (CFD) was chosen. In the approximation area equal to the true wind tunnel scale, Wing profiles formed at 0 to 20-degree attack angles are solved and equations are solved with the RNG k-Epsilon turbulence model. With Ansys Mesher, the grid development process was carried out, the solution stage and the result show operations were carried out with the CFD Post software. The study of the low velocity and high transport wing profiles, the drag coefficient, the lift coefficient, and the effect on the lift-drag ratio were studied using a numerical procedure. After the high efficiency of wing profiles was obtained, the production of a selected profile was started by making a static examination.
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Négyesi, Gábor, József Lóki, Botond Buró, Boglárka Bertalan-Balázs, and László Pásztor. "Wind erosion researches in Hungary – past, present and future possibilities." Hungarian Geographical Bulletin, October 3, 2019, 223–40. http://dx.doi.org/10.15201/hungeobull.68.3.2.
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Wind erosion is one of the most important land degradation processes in Hungary in the areas with low yearly precipitation values. The total land area suffering from wind erosion is approximately 10,000 km2, 10 per cent of the country area. Observations and discussions on wind erosion and its negative impacts in Hungary started in the last century. Since the 1950s, scientists investigated wind erosion processes and its role in the evolution of alluvial fans in an integrative way, including laboratory measurements and field observations with respect to the stabilization and utilization of soils in agricultural areas. Since the late 2000s, there is an increasing demand worldwide to characterize the role of climate change and human activities in triggering land degradation processes. Studies have been conducted to investigate the mechanics, causes and control techniques related to wind erosion applying laboratory and field wind tunnel simulation tests and field observations. Some encouraging achievements have been made. In this paper we summarize the main research results of wind erosion research, and put forward some perspectives and suggestions on the problems of wind erosion research and control practices in Hungary.
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"Tracers of air-sea gas exchange." Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences 325, no. 1583 (May 25, 1988): 93–103. http://dx.doi.org/10.1098/rsta.1988.0045.
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The flux of gas across the air-sea interface is determined by the product of the interfacial concentration difference driving the exchange and a rate constant, often termed the transfer velocity. The concentration-difference term is generally obtained by direct measurement, whereas more indirect approaches are required to estimate the transfer velocity and its variation as a function of controlling parameters such as wind and sea state. Radioactive tracers have proved particularly useful in the estimation of air-sea transfer velocities and, recently, stable purposeful tracers have also started to be used. In this paper the use of the following tracers to determine transfer velocities at the sea surface is discussed: natural and bomb-produced 14 C, dissolved oxygen, 222 Rn and sulphur hexafluoride. Other topics covered include the relation between transfer velocity and wind speed as deduced from tracer and wind-tunnel studies, and the discrepancy between transfer velocities determined by using tracers and from eddy correlation measurements in the atmosphere.
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Wurm, B., A. Schulz, H. J. Bauer, and M. Gerendas. "Impact of Swirl Flow on the Cooling Performance of an Effusion Cooled Combustor Liner." Journal of Engineering for Gas Turbines and Power 134, no. 12 (October 11, 2012). http://dx.doi.org/10.1115/1.4007332.
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An experimental study on combustor liner cooling of modern direct lean injection combustion chambers using coolant ejection from both effusion cooling holes and a starter film has been conducted. The experimental setup consists of a generic scaled three sector planar rig in an open loop hot gas wind tunnel, which has been described earlier in Wurm et al. (2009, “A New Test Facility for Investigating the Interactions Between Swirl Flow and Wall Cooling Films in Combustors, Investigating the Interactions Between Swirl Flow and Wall Cooling Films in Combustors,” ASME Paper No. GT2009-59961). Experiments are performed without combustion. Realistic engine conditions are achieved by applying engine-realistic Reynolds numbers, Mach numbers, and density ratios. A particle image velocimetry (PIV) measurement technique is employed, which has been adjusted to allow for high resolution near wall velocity measurements with and without coolant ejection. As the main focus of the present study is a deeper understanding of the interaction of swirl flows and near wall cooling flows, wall pressure measurements are performed for the definition of local blowing ratios and to identify the impact on the local cooling performance. For thermal investigations an infrared thermography measurement technique is employed that allows high resolution thermal studies on the effusion cooled liner surface. The effects of different heat shield geometry on the flow field and performance of the cooling films are investigated in terms of near wall velocity distributions and film cooling effectiveness. Two different heat shield configurations are investigated which differ in shape and inclination angle of the so called heat shield lip. Operating conditions for the hot gas main flow are kept constant. The pressure drop across the effusion cooled liner is varied between 1% and 3% of the total pressure. Results show the impact of the swirled main flow on the stability of the starter film and on the effusion cooling performance. Stagnation areas which could be identified by wall pressure measurements are confirmed by PIV measurements. Thermal investigations reveal reduced cooling performance in the respective stagnation areas.
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Aimo, A., G. Vergaro, S. Moscardini, D. Puccianti, V. Castiglione, F. Gentile, I. Fabiani, et al. "Prevalence of amyloid transthyretin cardiomyopathy in elderly subjects from the general population: first results from the CATCH study." European Heart Journal 43, Supplement_2 (October 1, 2022). http://dx.doi.org/10.1093/eurheartj/ehac544.1758.
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Abstract Background Amyloid transthyretin cardiomyopathy (ATTR-CM) has become treatable. Wild-type ATTR-CM is an age-related disorder. Establishing the exact prevalence of ATTR-CM in elderly subjects from the general population may be useful for healthcare providers and policy makers alike. Methods The Characterizing the burden of Amyloid Transthyretin CardiomyopatHy in the elderly (CATCH) study is a population screening on all subjects aged ≥65 years followed by general practitioners working in a part of Tuscany (Italy) where there is no cluster of variant ATTR. The study started on March 12, 2021 and is ongoing. The first step of the evaluation includes clinical history and physical examination, electrocardiogram, transthoracic echocardiogram, and blood sampling with measurement of N-terminal pro-B-type natriuretic peptide and high-sensitivity (hs) troponin T. The following elements are searched: 1) any clinical red flag of amyloidosis (history of carpal tunnel syndrome, lumbar spine stenosis, etc.), 2) interventricular septal thickness ≥12 mm or other echocardiographic red flags, 3) hs-troponin T higher than the upper reference limit (14 ng/L). Patients with any of these elements are referred to a second step including diphosphonate scintigraphy and the search for a monoclonal protein in the serum and urine. The standard diagnostic workup for CA is then followed until the diagnosis is confirmed or discarded. Results As of October 13, 2021, 514 subjects ≥65 years have been evaluated for possible participation. Among them, 135 (26%) could not be contacted, were reluctant to enter the study, died before being contacted, or were bedridden. Out of the other 379 subjects, 329 (87%) have already undergone the first step. Forty percent of individuals (n=132) have been referred to the second step. Thirteen subjects have declined (10%); 69 patients have undergone diphosphonate scintigraphy and the search for a monoclonal protein (while the other 50 are awaiting these exams). Two subjects showed an intense myocardial uptake of the diphosphonate tracer (Perugini score 2–3) and no monoclonal protein, and were then diagnosed with ATTR-CM. They were both women, aged 83 and 78 years, both mildly symptomatic for dyspnea (New York Heart Association II) and with unexplained hypertrophy. The search for TTR gene mutation was negative in the first case and is still ongoing in the second. Based on these preliminary data, the prevalence of ATTR-CM in the elderly population can be calculated as 2/266=0.8% (Figure 1). Conclusions The CATCH study is expected to enroll at least 1,000 subjects and will provide the first data on the epidemiology of ATTR-CM in elderly subjects. Based on an interim analysis, almost 1 in 100 individuals ≥65 years has ATTR-CM. Funding Acknowledgement Type of funding sources: None.
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Aimo, Alberto, Giuseppe Vergaro, Vincenzo Castiglione, Francesco Gentile, Assunta Agazio, Eleonora Benelli, Daniela Puccianti, et al. "541 Prevalence of amyloid transthyretin cardiomyopathy in elderly subjects from the general population: first results from the catch study." European Heart Journal Supplements 23, Supplement_G (December 1, 2021). http://dx.doi.org/10.1093/eurheartj/suab142.002.
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Abstract Aims Amyloid transthyretin cardiomyopathy (ATTR-CM) has become treatable. Wild-type ATTR-CM is an age-related disorder. Establishing the exact prevalence of ATTR-CM in elderly subjects from the general population may be useful for healthcare providers and policy makers alike. Methods and results The characterizing the burden of Amyloid Transthyretin CardiomyopatHy in the elderly (CATCH) study is a population screening on all subjects aged ≥65 years followed by general practitioners working at the Casa della Salute in Terricciola, in an area of Tuscany where there is no cluster of variant ATTR. The study started on 12 March 2021 and is ongoing. The first step of the evaluation includes clinical history and physical examination, electrocardiogram, transthoracic echocardiogram, and blood sampling with measurement of N-terminal pro-B-type natriuretic peptide and high-sensitivity (hs) troponin T. The following elements are searched: (i) any clinical red flag of amyloidosis (history of carpal tunnel syndrome, lumbar spine stenosis, etc.), (ii) interventricular septal thickness ≥12 mm or other echocardiographic red flags, and (iii) hs-troponin T higher than the upper reference limit (14 ng/l). Patients with any of these elements are referred to a second step including diphosphonate scintigraphy and the search for a monoclonal protein in the serum and urine. The standard diagnostic workup for CA is then followed until the diagnosis is confirmed or discarded. As of 31 October 2021, 514 subjects ≥65 years have been evaluated for possible participation. Among them, 135 (26%) could not be contacted, were reluctant to enter the study, died before being contacted, or were bedridden. Out of the other 379 subjects, 329 (87%) have already undergone the first step. Forty percent of individuals (n = 132) have been referred to the second step. Thirteen subjects have declined (10%); 69 patients have undergone diphosphonate scintigraphy, and the search for a monoclonal protein (while the other 50 are awaiting these exams). Two subjects showed an intense myocardial uptake of the diphosphonate tracer (Perugini score 2–3) and no monoclonal protein, and were then diagnosed with ATTR-CM. They were both women, aged 83 and 78 years, both mildly symptomatic for dyspnoea (New York Heart Association II) and with unexplained hypertrophy. The search for TTR gene mutation was negative in the first case and is still ongoing in the second. Based on these preliminary data, the prevalence of ATTR-CM in the elderly population can be calculated as 2/266 = 0.8% (Figure). Conclusions The CATCH study is expected to enroll at least 1000 subjects and will provide the first data on the epidemiology of ATTR-CM in elderly subjects. Based on an interim analysis, almost 1 in 100 individuals ≥65 years has ATTR-CM.