Journal articles: 'Rectangular wind tunnels'

1

Raupach, MR, and JF Leys. "Aerodynamics of a portable wind erosion tunnel for measuring soil erodibility by wind." Soil Research 28, no. 2 (1990): 177. http://dx.doi.org/10.1071/sr9900177.

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Portable wind erosion tunnels must satisfy several aerodynamic criteria to ensure that the flow within them acceptably reproduces the atmospheric flow causing natural wind erosion. We define these criteria and use them to assess the flow and turbulence in two alternative designs of portable wind erosion tunnel: the first has a working section with an approximately triangular, 'tent-shaped' cross section, while the second has a conventional, rectangular working section. The measurements were made with Pitot-static tubes and X-configuration hot-wire anemometers, over stable (non-eroding) rough surfaces, mainly mowed grass of height 1 cm. We found that, with careful attention to flow conditioning elements such as honeycombs and tripping fences, an acceptable flow can be achieved in the rectangular tunnel. The flow in the tent-shaped tunnel is less satisfactory, exhibiting departures from the logarithmic wind profile law which depend on the surface roughness.

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Baumeister, K. J. "Reverberation Effects on Directionality and Response of Stationary Monopole and Dipole Sources in a Wind Tunnel." Journal of Vibration and Acoustics 108, no. 1 (January 1, 1986): 82–90. http://dx.doi.org/10.1115/1.3269307.

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Analytical solutions for the three-dimensional inhomogeneous wave equation with flow in a hardwall rectangular wind tunnel and in the free field are presented for a stationary monopole noise source. Dipole noise sources are calculated by combining two monopoles 180 deg out of phase. Numerical calculations for the modal content, spectral response and directivity for both monopole and dipole sources are presented. In addition, the effect of tunnel alterations, such as the addition of a mounting plate, on the tunnels reverberant response are considered. In the frequency range of practical importance for the turboprop response, important features of the free field directivity can be approximated in a hardwall wind tunnel with flow if the major lobe of the noise source is not directed upstream. However, for an omnidirectional source, such as a monopole, the hardwall wind tunnel and free field response will not be comparable.

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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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Wiriadidjaja, Surjatin, Azmin Shakrine Mohd Rafie, Fairuz Izzuddin Romli, and Omar Kassim Ariff. "Aerodynamic Interference Correction Methods Case: Subsonic Closed Wind Tunnels." Applied Mechanics and Materials 225 (November 2012): 60–66. http://dx.doi.org/10.4028/www.scientific.net/amm.225.60.

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The approach to problems of wall interference in wind tunnel testing is generally based on the so-called classical method, which covers the wall interference experienced by a simple small model or the neo-classical method that contains some improvements as such that it can be applied to larger models. Both methods are analytical techniques offering solutions of the subsonic potential equation of the wall interference flow field. Since an accurate description of wind tunnel test data is only possible if the wall interference phenomena are fully understood, uncounted subsequent efforts have been spent by many researchers to improve the limitation of the classical methods by applying new techniques and advanced methods. However, the problem of wall interference has remained a lasting concern to aerodynamicists and it continues to be a field of active research until the present. The main objective of this paper is to present an improved classical method of the wall interference assessment in rectangular subsonic wind tunnel with solid-walls.

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Quinn, Daniel B., Anthony Watts, Tony Nagle, and David Lentink. "A new low-turbulence wind tunnel for animal and small vehicle flight experiments." Royal Society Open Science 4, no. 3 (March 2017): 160960. http://dx.doi.org/10.1098/rsos.160960.

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Our understanding of animal flight benefits greatly from specialized wind tunnels designed for flying animals. Existing facilities can simulate laminar flow during straight, ascending and descending flight, as well as at different altitudes. However, the atmosphere in which animals fly is even more complex. Flow can be laminar and quiet at high altitudes but highly turbulent near the ground, and gusts can rapidly change wind speed. To study flight in both laminar and turbulent environments, a multi-purpose wind tunnel for studying animal and small vehicle flight was built at Stanford University. The tunnel is closed-circuit and can produce airspeeds up to 50 m s −1 in a rectangular test section that is 1.0 m wide, 0.82 m tall and 1.73 m long. Seamless honeycomb and screens in the airline together with a carefully designed contraction reduce centreline turbulence intensities to less than or equal to 0.030% at all operating speeds. A large diameter fan and specialized acoustic treatment allow the tunnel to operate at low noise levels of 76.4 dB at 20 m s −1 . To simulate high turbulence, an active turbulence grid can increase turbulence intensities up to 45%. Finally, an open jet configuration enables stereo high-speed fluoroscopy for studying musculoskeletal control in turbulent flow.

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Razak, Norizham Abdul, Thomas Andrianne, and Grigorios Dimitriadis. "Flutter and Stall Flutter of a Rectangular Wing in a Wind Tunnel." AIAA Journal 49, no. 10 (October 2011): 2258–71. http://dx.doi.org/10.2514/1.j051041.

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Wei, Lian-Jiang, Meng-Wei Wang, Sheng Li, and Zong-Kang Wei. "Line wind speed distribution model of rectangular tunnel cross-section." Thermal Science 23, no. 3 Part A (2019): 1513–19. http://dx.doi.org/10.2298/tsci180707218w.

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Accurate monitoring of the tunnel wind speed plays a key role in achieving intelligent mine ventilation. Based on the difficulty faced in precise reflection of the average tunnel wind speed by point wind speed monitoring, this paper puts forward a method for accurate monitoring the tunnel wind speed by large-span ultrasonic linear wind speed sensor based on the method of the time difference. Besides, as to the core problem of representing the average section wind speed by section-linear wind speed, the distribution rules of section wind speed in rectangular tunnel with various support forms is studied through combing theoretical analysis and experimental verification. The results could be well applied to rapid determination of ventilation parameters in other coal mines, which is better for the ventilation management of mines.

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Zurriati, M. Ali, Kuntjoro Wahyu, Wirachman Wisnoe, and E. M. Nasir Rizal. "The Effect of Canard on Aerodynamics of Blended Wing Body." Applied Mechanics and Materials 110-116 (October 2011): 4156–60. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.4156.

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This paper describes the wind tunnel testing of a Blended Wing Body (BWB) with rectangular canards and twisted wing (Baseline II E2 configuration) developed in Universiti Teknologi MARA (UiTM). The experiment work was carried out in UiTM low speed wind tunnel using 1:6 scaled model of BWB at Mach 0.1. The testing is conducted for canard’s deflection angle between 0° to +20. The results show by adding the canard surface to the BWB’s body, at 12 degree and higher angles of attack,α there will be a slight increment in lift. Maximum lift-to-drag ratio decreases with increasing canard surface deflection. Also, by adding the canard surface, the value of moment at zero lift,CM,0 is increased.

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Jamei, Saeed, Adi Maimun, Rasul Niazmand Bilandi, Nor Azwadi, Simone Mancini, Luigi Vitiello, and Maria De Carlini. "Wake behind a Compound Wing in Ground Effect." Journal of Marine Science and Engineering 8, no. 3 (March 1, 2020): 156. http://dx.doi.org/10.3390/jmse8030156.

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Flow structure is a crucial point for the conceptual design of Wing-in-Ground effect (WIG) crafts. In this study, pressure distributions around a compound wing, velocity and the turbulent intensity distribution in the wake area after trailing of the wing, have been investigated numerically. Computational simulations were completed regarding various angles of attack in-ground-effect. Two parts made up the compound wing: The first composed by one rectangular wing in the center, the second composed by a reverse taper wing, consisting of an anhedral angle at the side. A realizable k-ε turbulent model exhibited the flow field in the physical domain about the wing surface. The numerical results of the compound wing were validated using the data provided by wind tunnel tests. The flow structures around the compound wing were compared with that of a rectangular wing for different conditions. It was found that the pressure distribution on the rectangular wing was weaker than at the lower surface for the compound wing. However, the suction effect on the upper surface of the rectangular wing was higher. Also, the velocity defect and the turbulence level in the wake area was greater behind the compound wing.

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Lipecki, Tomasz. "Wind action on flat roofs." Budownictwo i Architektura 13, no. 2 (June 11, 2014): 239–46. http://dx.doi.org/10.35784/bud-arch.1901.

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The paper deals with the wind action on flat roofs of rectangular shapes which can be considered for medium-rise and high-rise buildings. Distributions of mean pressure coefficient Cp on flat roofs were measured. All analyses were based on model measurements which had been performed in the boundary layer wind tunnel in Wind Engineering Laboratory of Cracow University of Technology. Vertical, fixed in the floor of the wind tunnel on the turn table rectangular prisms of the ratio of cross-section dimensions 1:2 and 1:4 were investigated. Measurements were carried out for the angle of wind attack in the range 0°-90°, every 15°. The influence of the wind structure on pressures was investigated in six different cases of the approaching wind.

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Zuo, D., C. W. Letchford, and S. Wayne. "Wind tunnel study of wind loading on rectangular louvered panels." Wind and Structures An International Journal 14, no. 5 (September 25, 2011): 449–63. http://dx.doi.org/10.12989/was.2011.14.5.449.

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Воеводин, А. В., Д. А. Петров, А. С. Петров, В. Г. Судаков, and Г. Г. Судаков. "Численные исследования особенностей обтекания крыла в режиме бафтинга." Письма в журнал технической физики 46, no. 13 (2020): 11. http://dx.doi.org/10.21883/pjtf.2020.13.49583.18285.

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The numerical method validation using the Reynolds equations and calculations were made for the case of infinite aspect ratio rectangular wing, which is streamed by a transonic unbounded air flow in buffet regime. It is shown, that instead of 2D flow, a periodical flow along the lateral direction is realized. Furthermore, the oscillations in time along the longitudinal direction (buffet) take place. The presence of the side wind tunnel walls deforms this periodical structure and changes the buffet frequency. Calculations of the wing-body combination flow show that the oscillations take place inside the restricted wing area both along longitudinal and lateral directions.

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Tao, Changfa, Xishi Wang, and Xiaonan Zhang. "EFFECTS OF TRANSVERSE AIR FLOW ON MASS LOSS RATE OF ALCOHOL POOL FIRES IN AN INCLINED WIND TUNNEL." Journal of Civil Engineering and Management 21, no. 6 (June 9, 2015): 798–803. http://dx.doi.org/10.3846/13923730.2014.893920.

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In order to study the effects of inclined wind direction on combustion characteristics of alcohol pool fires, an inclinable wind tunnel was developed and used for providing venting wind with different directions. The wind tunnel can be sloped from 0° to 30° while the fuel pan is kept horizontal inside the tunnel. The wind speed can be altered from 0 to 3.0 m/s. The mass burning rate of square, rectangular and circular alcohol pool fires under different wind direction have been studied experimentally. The results show that the mass burning rate increases faster with increasing the slope angle of the wind tunnel and increasing the downstream edge length of the pool.

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Xiao, Tian Yin. "Power Spectral Density Model of Torsional Dynamic Wind Loads on Tall Buildings." Applied Mechanics and Materials 164 (April 2012): 433–36. http://dx.doi.org/10.4028/www.scientific.net/amm.164.433.

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9 models of tall buildings with different rectangular cross-sections are tested in a wind tunnel. After processing and analyzing the measured data of fluctuating pressure on the models, the effects of models’height, aspect ratio, side ratio on the power spectra of torsional wind loads are studied. New formulas of power spectral density of torsional wind loads are proposed by curve fitting method. The applicability of the formulas has been verified by the results from the wind tunnel test.

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Guzmán-Solís, Vladimir, Adrian Pozos-Estrada, and Roberto Gómez. "Experimental study of wind-induced shear, bending, and torsional loads on rectangular tall buildings." Advances in Structural Engineering 23, no. 14 (June 9, 2020): 2982–95. http://dx.doi.org/10.1177/1369433220927280.

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To investigate wind-induced torsional loads on rectangular tall buildings, five rigid scale models were tested in an atmospheric boundary layer wind tunnel. Each model was built with identical plan dimensions but different aspect ratios. Two terrain categories were experimentally simulated in the wind tunnel to evaluate each model under different wind directions. From synchronized wind pressure measurements, the values for the shear wind force, bending moment, and torsion moment at the base of each model were calculated. The results were normalized in terms of mean shear, bending, and torque coefficients. Variations of the coefficients obtained with respect to the aspect ratio of the models tested were analyzed. Based on the experimental results, a new parametric equation to estimate the torque coefficients at the base of rectangular tall buildings as a function of aspect ratio and wind direction was proposed. The base torque coefficients obtained with the proposed equation are in good agreement with the experimental results.

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Wang, Qian, Qing Hao Meng, Yan Peng Man, Jia Ying Wang, Ming Zeng, and Wei Li. "Simulation of Outdoor Near-Surface Airflows Based on a Wind Tunnel with Multiple Actively-Controlled Fans." Advanced Materials Research 807-809 (September 2013): 102–5. http://dx.doi.org/10.4028/www.scientific.net/amr.807-809.102.

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In this paper, multiple actively-controlled fans generate outdoor near-surface airflow in a wind tunnel with once-through openings. The wind tunnel system consists of 6 groups of fans installed on rotatable plates in a rectangular inlet. We use a stochastic strategy to control the fans and the rotatable plates to regulate wind speed and direction that fluctuate according to the pattern of outdoor near-surface airflow. We utilize the statistics and multi-scale methods to analyze the effectiveness of the strategy for simulating the outdoor near-surface airflow. We provide comparison studies on the multi-scale entropy of wind speed, wind stability, and the standard deviation of directions between out-door wind and the tunnel generated wind. Results show that a flow field akin to the near-surface airflow in outdoor environments can be produced by the wind tunnel using the stochastic control strategy, which can be considered as a reliable experiment environment for gas pollution source localization research in outdoor near-surface breeze conditions.

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Mikhailov, Yu S., and Yu G. Stepanov. "SIMULATION OF 2D FLOW AROUND OF AIRFOILS AT LOW-SPEED WIND TUNNEL WITH OPEN JET TEST-SECTION." Civil Aviation High TECHNOLOGIES 22, no. 1 (February 27, 2019): 51–62. http://dx.doi.org/10.26467/2079-0619-2019-22-1-51-62.

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At present, there is a great interest in the development of new airfoils for wind turbines and high-lift wings of unmanned aerial vehicles (UAV). The requirements for such airfoils differ from conventional aircraft airfoils, because of structural reasons and extreme operating conditions. So, wind turbine airfoils operate frequently under fully separated flow when stall is used for power regulation at high wind speeds. At the same time design of airfoils for wings UAV poses the problem of availability of high-lift at low Reynolds number. Modern airfoils are to a large extent developed from numerical methods. However, the complex flow conditions such as separation at high angles of attack, laminar separation bubbles and the transition from laminar to turbulent flow are difficult to predict accurately. Hence, testing of airfoils at a two-dimensional condition is an important phase in airfoil design. The development and validation of a 2D testing facility for investigation of single and multi-element airfoils in the wind tunnel Т-102 with open test section are considered in this article. T-102 is a continuous-operation, closed-layout wind tunnel with two reverse channels. The test section has an elliptical cross-section of 4 ×2,33 m and a length of 4 m. Two big flat panels of the L × H=3 ×3,9 m size installed upright on balance frame aligned with the free stream are used for simulating two-dimensional flow in the tunnel test section. The airfoil section in the layout of a rectangular wing is mounted horizontally between flat panels with minimum gaps to ensure 2D flow conditions. The aerodynamic forces and pitch moment acting on the model were measured by wind tunnel balance. To determine boundary corrections for a new test section of wind tunnel, the experimental investigation of three geometrically similar models has been executed. The use of boundary corrections has provided good correlation of the test data of airfoil NACA 6712 with the results obtained from the wind tunnel except for lift and drag coefficient values at high angles of attack.

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Błazik-Borowa, Ewa, Jarosław Bęc, Tomasz Nowicki, Tomasz Lipecki, and Jacek Szulej. "Measurements of 2-D flow parameters around rectangular prisms arranged at the ground." Budownictwo i Architektura 3, no. 2 (December 11, 2008): 033–51. http://dx.doi.org/10.35784/bud-arch.2321.

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Measurements of 2-D flows around a square and a rectangle (ratio 2:1) in wind tunnel have been presented in this paper. The results of these measurements presented here are pressure and standard deviation distributions on the models’ walls, components of velocity vectors and statistical moments for fluctuations of velocity in the wind tunnel measuring space. The values of parameters have been presented in graphs and subsequently used in a comparative analysis of the flows around both models.

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Roy, Aritras, R. Vinoth Kumar, and Rinku Mukherjee. "Experimental validation of numerical decambering approach for flow past a rectangular wing." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 234, no. 9 (April 6, 2020): 1564–82. http://dx.doi.org/10.1177/0954410020916311.

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Experimental investigation on two rectangular wings with NACA0012 and NACA4415 profiles is performed at different Reynolds numbers to understand their aerodynamic behaviours at a high α regime. In-house developed numerical code VLM3D is validated using this experimental result in predicting the aerodynamic characteristics of a rectangular wing with cambered and symmetrical wing profile. The sectional coefficient of lift ([Formula: see text]) obtained from the numerical approach is used to study the variation in spanwise lift distribution. The lift and moment characteristics obtained from wind tunnel experiments are plotted, and change in the maximum coefficient of lift ([Formula: see text]) and stall angle ( α stall) are studied for both of the wing sections. A significant addition to the novelty of the present experiments is to provide some comparison of the numerical induced drag coefficient, [Formula: see text] with experimentally fitted model coefficients using least square technique. A novel method is used to examine the aerodynamic hysteresis at high angles of attack. The area included in the lift- Re curve loop is a measure of aerodynamic efficiency, and its variation with angle of attack and wing plan forms is studied.

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Yaman, Kemal. "Subsonic Flutter of Cantilever Rectangular PC Plate Structure." International Journal of Aerospace Engineering 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/9212364.

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Flutter characteristics of cantilever rectangular flexible plate structure under incompressible flow regime are investigated by comparing the results of commercial flutter analysis program ZAERO©with wind tunnel tests conducted in Ankara Wind Tunnel (ART). A rectangular polycarbonate (PC) plate, 5 × 125 × 1000 mm in dimension, is used for both numerical and experimental investigations. Analysis and test results are very compatible with each other. A comparison between two different solution methods (g-methodandk-method) of ZAERO©is also done. It is seen that thek-methodgives a closer result than the other one. However,g-method results are on a conservative side and it is better to use conservative results, namely,g-method results. Even if the modal analysis results are used for the flutter analysis for this simple structure, a modal test should be conducted in order to validate the modal analysis results to have accurate flutter analysis results for more complicated structures.

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Mabey, D. G., B. L. Welsh, and C. R. Pyne. "A summary of measurements of steady and oscillatory pressures on a rectangular wing." Aeronautical Journal 92, no. 911 (January 1988): 10–28. http://dx.doi.org/10.1017/s0001924000021795.

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Summary This paper describes a series of steady and time-dependent pressure measurements on a half-model of a rectangular wing of aspect ratio 4. The wing was mounted on a half-body attached to a sidewall of the RAE 8 x 8 ft wind tunnel and the tests were made at Mach numbers of 0·20, 0·42, 0·70, 0·80 and 0·85 with fixed transition and a Reynolds number of about 2·5 x 106 at the highest Mach number. The wing was oscillated about its mid-chord axis at four frequencies giving frequency parameters up to 1·15 at M = 0·20 and 0·25 at M = 0·85. The static angle of incidence was varied from –10° to + 10°. Selected mean and oscillatory measurements are offered as a challenge to computational fluid dynamicists for this simple three-dimensional configuration. Comparisons are made with calculations by means of subsonic linearised theory and recent transonic small perturbation methods. The measurements are of particular interest at transonic speeds, where both attached and incipient separated flows are considered.

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Zizkovsky, Nikola, and Jan Klesa. "Wing-Propeller Interaction." MATEC Web of Conferences 304 (2019): 02019. http://dx.doi.org/10.1051/matecconf/201930402019.

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Paper describes the effect of the distributed electric propulsion system (DEP) on the aerodynamic characteristics of the airplane wing. Using CFD simulation is described the influence of the wake of the propeller on the wing for various ratios of the propeller diameter to the wing chord. Unlike the normal case of wing-propeller interaction, periodic boundary conditions are used, i.e. a rectangular wing with infinite span with propellers installed periodically its span is considered. A wind tunnel experiment will be used to verify the calculations. Propeller thrust is set to compensate for airplane drag in horizontal flight, i.e. equal to the wing segment drag, which is increased by the corresponding part of the expected drag of other parts of the airplane. The increase of the drag was determined by the aerodynamic design of a generic airplane with DEP. The benefit of the work are the input data usable for the conceptual design of the airplane wing with DEP.

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DWIVEDI, Y. D. "Flow Field Study of Bio-Inspired Corrugated Airfoils at Low Reynolds Number with Different Peak Shapes." INCAS BULLETIN 12, no. 3 (September 1, 2020): 87–100. http://dx.doi.org/10.13111/2066-8201.2020.12.3.7.

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This study is intended to understand the fluid flow behaviour of a bio inspired corrugated wing obtained from the mid span of the dragonfly wing with different peak shapes of the corrugations. The aerodynamic effect due to variation of the shape of the first peak is studied with triangular and a curved peak shapes. The coordinates of the corrugated wing of the dragonfly were obtained from the existing literature and scaled up 1:50 to do the computational work on it. The corrugated wing was modeled by using a modeling software, the meshing was done by using ICEMCFD with a rectangular block meshing and simulated in Ansys Fluent software at 35000 Reynolds number and angles of attack ranging from 4° to 12°. The k-ε turbulence modeling was deployed to capture turbulence in the tested domain. The boundary conditions and size of the domain were selected as per available experimental wind tunnel setup. The flow characteristics like pressure and velocity of the triangular and curved peaks were obtained computationally and compared with each other having same geometrical parameters. The simulated results showed that the curved peak performed aerodynamically better than the triangular peak. The leading edge vortices were observed in both models trapped in the trough of the first valley with some different intensity. The validation of the computational flow results was done by existing experimental flow visualization in a wind tunnel and both results agree with each other.

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Zhang, W., J. J. Wang, and Z. Wu. "Experimental investigations on the application of lift enhancement devices to forward-swept aircraft model." Aeronautical Journal 110, no. 1108 (June 2006): 361–67. http://dx.doi.org/10.1017/s0001924000001275.

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Abstract The force measurements were conducted in low speed wind tunnel to investigate the effects of the scale, shape and the installation type of Gurney flap on a forward-swept aircraft model. The results indicated that both rectangular and triangular Gurney flaps can enhance the lift coefficient of the model tested, but with a little decrease of stall angle from 38° to 36°. The lift and drag coefficients increased with the Gurney flap scales. Meanwhile, the triangular Gurney flap can improve the aerodynamic performance more effectively when its high side is located near the wing root than the reverse installation with the low side near the wing root and the high side near the wing tip. Additionally, for the same Gurney flap, the model with smaller forward-swept angle can generate higher lift-enhancement in comparison with the larger forward-swept angle model.

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FUJIMORI, Atsushi, and Hirobumi OHTA. "Designs of a gust load alleviation system for a cantilevered elastic rectangular wing and wind-tunnel tests." Journal of the Japan Society for Aeronautical and Space Sciences 38, no. 441 (1990): 524–32. http://dx.doi.org/10.2322/jjsass1969.38.524.

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Li, Yi, Chao Li, Qiu-Sheng Li, Yong-Gui Li, and Fu-Bin Chen. "Refined Mathematical Models for Across-Wind Loads of Rectangular Tall Buildings with Aerodynamic Modifications." International Journal of Structural Stability and Dynamics 21, no. 09 (May 20, 2021): 2150131. http://dx.doi.org/10.1142/s0219455421501315.

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This paper aims to systematically study the across-wind loads of rectangular-shaped tall buildings with aerodynamic modifications and propose refined mathematic models accordingly. This study takes the CAARC (Commonwealth Advisory Aeronautical Research Council) standard tall building as a benchmark model and conducts a series of pressure measurements on the benchmark model and four CAARC models with different round corner rates (5%, 10%, 15% and 20%) in a boundary layer wind tunnel to investigate the across-wind dynamic loads of the typical tall building with different corner modifications. Based on the experimental results of the five models, base moment coefficients, power spectral densities and vertical correlation coefficients of the across-wind loads are compared and discussed. The analyzed results shown that the across-wind aerodynamic performance of the tall buildings can be effectively improved as the rounded corner rate increases. Taking the corner round rate and terrain category as two basic variables, empirical formulas for estimating the across-wind dynamic loads of CAARC standard tall buildings with various rounded corners are proposed on the basis of the wind tunnel testing results. The accuracy and applicability of the proposed formulas are verified by comparisons between the empirical formulas and the experimental results.

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WATANABE, Masahiro, Keisuke ITAI, and Kensuke HARA. "J052023 Flutter Analysis and Wind-Tunnel Experiments of Double Rectangular Sheets." Proceedings of Mechanical Engineering Congress, Japan 2013 (2013): _J052023–1—_J052023–5. http://dx.doi.org/10.1299/jsmemecj.2013._j052023-1.

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Tamaki, M., and T. Maruyama. "Comparison of wind loads on rectangular net house with numerical simulation and wind tunnel tests." Acta Horticulturae, no. 1312 (May 2021): 559–66. http://dx.doi.org/10.17660/actahortic.2021.1312.79.

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Michalcova, Vladimira, Sergej Kuznetsov, Jiri Brozovsky, and Stanislav Pospíšil. "Numerical and Experimental Investigations of Air Flow Turbulence Characteristics in the Wind Tunnel Contraction." Applied Mechanics and Materials 617 (August 2014): 275–79. http://dx.doi.org/10.4028/www.scientific.net/amm.617.275.

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Flow characteristics contraction of rectangular cross-section are investigated numerically and experimentally so as to gain an additional insight into the contraction design. They observed velocity field and turbulent intensity in the area of contraction and downstream of it. Individual numerical models sofware Ansys Fluent are evaluated and compared with measurements in a wind tunnel.

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Sumida, M., and S. Morita. "Wind Tunnel Tests on Aerodynamic Forces of Road Vehicles Under Unsteady Wind Conditions." International Journal of Automotive and Mechanical Engineering 15, no. 4 (December 25, 2018): 6064–77. http://dx.doi.org/10.15282/ijame.15.4.2018.25.0462.

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This paper describes the results obtained from a wind tunnel test on the aerodynamic characteristics of road vehicles subjected to unsteady wind. In order to study the aerodynamic response of vehicles under atmospheric fluctuations, the velocity of the wind has been simulated in a pulsating state, where vehicles at a constant speed are driving in air with large wind oscillation. On the other hand, we consider three types of vehicles: two types of the Ahmed model, with slant angles of 0° and 30°, and the basic rectangular-prism model. The effect of wind oscillation on the drag and lift forces acting on the vehicle models under a pulsating wind condition has been extracted by comparing it to the forces under steady wind conditions. The oscillation of the wind exerts a significant effect on the fluid forces, and the drag and lift forces change with time in a peculiar way, depending on the body shape of the vehicle.

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Peterka, J. A., Z. Tan, J. E. Cermak, and B. Bienkiewicz. "Mean and Peak Wind Loads on Heliostats." Journal of Solar Energy Engineering 111, no. 2 (May 1, 1989): 158–64. http://dx.doi.org/10.1115/1.3268302.

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Mean and peak wind loads on flat rectangular or circular heliostats were measured on models in a boundary layer wind tunnel which included an atmospheric surface layer simulation. Horizontal and vertical forces, moments about horizontal axes at the ground level and at the centerline of the heliostat, and the moment about the vertical axis through the heliostat center were measured. Results showed that loads are higher than predicted from results obtained in a uniform, low-turbulence flow due to the presence of turbulence. Reduced wind loads were demonstrated for heliostats within a field of heliostats and upper bound curves were developed to provide preliminary design coefficients.

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32

Wang, Ying Ge. "Vortex Characteristics of Heliostats’ Surface Wind Pressure under Resting Condition." Advanced Materials Research 953-954 (June 2014): 1463–66. http://dx.doi.org/10.4028/www.scientific.net/amr.953-954.1463.

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Flat rectangular heliostats’ surface wind pressure distribution under resting condition was analyzed via wind tunnel experiment results. The flow field characteristics of the mirror in parallel with the ground were combined to reveal the distribution cause of fluctuating pressure. Phenomena of columnar vortex and conical vortex formed from mirror’s flow field under wind angles 0° and 45° were aimed to explain their internal structure using theory of point vortex model. With power spectrum of peculiar points’ fluctuating wind pressure analyzed, the surface vortex characteristics were further elaborated. The above work revealed heliostats’ surface wind pressure characteristics under resting conditions, and established the theoretical basis of its design study.

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33

Lipecki, Tomasz, Ewa Błazik-Borowa, and Jarosław Bęc. "Wind structure influence on surface pressures of rectangular cylinders of cross-section dimensions 10 cm x 20 cm." Budownictwo i Architektura 10, no. 1 (June 11, 2012): 069–80. http://dx.doi.org/10.35784/bud-arch.2231.

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The paper deals with results of measurements which have been carried out in the wind tunnel. Vertical, fixed prism of the cross-section dimensions 10 cm x 20 cm was the object of the experiment. Distributions of mean wind pressure coefficient on the surface of the prism were accepted as results presentation. The following parameters of the wind structure were analysed: vertical mean wind speed profile, turbulence intensity profile, power spectral density functions with respect to their influence on pressure coefficient values. Changes of the angle of wind attack were taken into consideration.

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34

Amin, J. A., and A. K. Ahuja. "Effects of Side Ratio on Wind-Induced Pressure Distribution on Rectangular Buildings." Journal of Structures 2013 (August 12, 2013): 1–12. http://dx.doi.org/10.1155/2013/176739.

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This paper presents the results of wind tunnel studies on 1 : 300 scaled-down models of rectangular buildings having the same plan area and height but different side ratios ranging from 0.25 to 4. Fluctuating values of wind pressures are measured at pressure points on all surfaces of models and mean, maximum, minimum, and r.m.s. values of pressure coefficients are evaluated. Effectiveness of the side ratios of models in changing the surface pressure distribution is assessed at wind incidence angle of 0° to 90° at an interval of 15°. Side ratio of models has considerable effects on the magnitude and distribution of wind pressure on leeward and sidewalls but it has very limited effect on windward walls at wind incidence angle of 0°. For building models with constant cross section, change in side ratio does not significantly affect the general magnitude of peak pressures and peak suctions, but rather the wind angle at which they occur. The regression equation is also proposed to predict the mean pressure coefficient on leeward wall and side wall of rectangular models having different side ratios at 0° wind incidence angle.

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35

Ladas, Dimitrios I., Theodore Stathopoulos, and Efstratios Dimitrios Rounis. "Wind effects on the performance of solar collectors on rectangular flat roofs: A wind tunnel study." Journal of Wind Engineering and Industrial Aerodynamics 161 (February 2017): 27–41. http://dx.doi.org/10.1016/j.jweia.2016.12.008.

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Delaunay, D., D. Lakehal, C. Barré, and C. Sacré. "Numerical and wind tunnel simulation of gas dispersion around a rectangular building." Journal of Wind Engineering and Industrial Aerodynamics 67-68 (April 1997): 721–32. http://dx.doi.org/10.1016/s0167-6105(97)00113-x.

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37

Diehl, Steve R., Donald A. Burrows, Eric A. Hendricks, and Robert Keith. "Urban Dispersion Modeling: Comparison with Single-Building Measurements." Journal of Applied Meteorology and Climatology 46, no. 12 (December 1, 2007): 2180–91. http://dx.doi.org/10.1175/2006jamc1300.1.

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Abstract Two models have been developed to predict airflow and dispersion in urban environments. The first model, the Realistic Urban Spread and Transport of Intrusive Contaminants (RUSTIC) model, is a fast-running urban airflow code that rapidly converges to a numerical solution of a modified set of the compressible Navier–Stokes equations. RUSTIC uses the k–ω turbulence model with a buoyancy production term to handle atmospheric stability effects. The second model, “MESO,” is a Lagrangian particle transport and dispersion code that predicts concentrations of a released chemical or biological agent in urban or rural areas. As a preliminary validation of the models, concentrations simulated by MESO are compared with experimental data from wind-tunnel testing of dispersion around both a multistory rectangular building and a single-story L-shaped building. For the rectangular building, trace gas is forced out at the base of the downwind side, whereas for the L-shaped building, trace gas is forced out of a side door in the inner corner of the “L.” The MESO–RUSTIC combination is set up with the initial conditions of the wind-tunnel experiment, and the steady-state concentrations simulated by the models are compared with the wind-tunnel data. For the multistory building, a dense set of detector locations was available downwind at ground level. For the L-shaped building, concentration data were available at three heights in a lateral plane at a distance of one building height downwind of the lee side. A favorable comparison between model simulations and test data is shown for both buildings.

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Chang, Ying, Lin Zhao, and Yaojun Ge. "Theoretical and testing investigation of wind–rain coupling loads on some typical bluff bodies." Advances in Structural Engineering 22, no. 1 (June 18, 2018): 156–71. http://dx.doi.org/10.1177/1369433218781953.

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The article presents a mathematical theoretical framework and fitting parameters with aspects of joint probability distribution of wind and rain, separate wind and rain action, and coupled wind and rain effects on steady and unsteady forces acting on some typical bluff bodies. Gumbel and copula functions were first selected to describe the joint probability distribution of wind speed and rain intensity. Then, two models, a raindrop impact model and an equivalent air density model, were adopted to quantify the loading action considering only separate wind and rain action, and simplified coupled effects with superimposition of wind and rain show that it would be accurate enough to neglect separated rain influence in steady wind and rain loading conditions. Furthermore, wind tunnel testing has been carried out under coupled wind and rain conditions with the help of a high-precision raining simulation system in TJ-1 wind tunnel on various reduced-scale models with some typical cross sections, such as circular and rectangular, thin plate, and streamlined box, and their aerodynamic loading and wind–rain-induced performance have been systematically compared. It has thus been found that the coupling effects of wind and rain should not be neglected in steady and unsteady force models.

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Khalid, Mahmood, Khalid A. Juhany, and Salah Hafez. "Computational modeling of the flow in a wind tunnel." Aircraft Engineering and Aerospace Technology 90, no. 1 (January 2, 2018): 175–85. http://dx.doi.org/10.1108/aeat-05-2016-0072.

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Purpose The purpose of this paper is to use a computational technique to simulate the flow in a two-dimensional (2D) wind tunnel where the effect of the solid walls facing the model has been addressed using a porous geometry so that interference arriving at the solid walls are duly damped and a flow suction procedure has been adopted at the side wall to minimize the span-wise effect of the growing side wall boundary layer. Design/methodology/approach A CFD procedure based on discretization of the Navier–Stokes equations has been used to model the flow in a rectangular volume with appropriate treatment for solid walls of the confined volume in which the model is placed. The rectangular volume was configured by stacking O-Grid sections in a span-wise direction using geometric growth from the wall. A porous wall condition has been adapted to counter the wall interference signatures and a separate suction procedure has been implemented for reducing the side wall boundary layer effects. Findings It has been shown that through such corrective measures, the flow in a wind tunnel can be adequately simulated using computational modeling. Computed results were compared against experimental measurements obtained from IAR (Institute for Aerospace, Canada) and NAL (National Aeronautical Laboratory, Japan) to show that indeed appropriate corrective means may be adapted to reduce the interference effects. Research limitations/implications The solutions seemed to converge a lot better using relatively coarser grids which placed the shock locations closer to the experimental values. The finer grids were more stiff to converge and resulted in reversed flow with the two equation k-w model in the region where the intention was to draw out the fluid to thin down the boundary layer. The one equation Spalart–Allmaras model gave better result when porosity and wall suction routines were implemented. Practical implications This method could be used by industry to point check the results against certain demanding flow conditions and then used for more routine parametric studies at other conditions. The method would prove to be efficient and economical during early design stages of a configuration. Originality/value The method makes use of an O-grid to represent the confined test section and its dual treatment of wall interference and blockage effects through simultaneous application of porosity and boundary layer suction is believed to be quite original.

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40

Skews, B. W. "Autorotation of rectangular plates." Journal of Fluid Mechanics 217 (August 1990): 33–40. http://dx.doi.org/10.1017/s0022112090000611.

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A series of tests have been conducted on the autorotation of plates of rectangular section and thickness to chord ratios of from 0.1 to 1.0. The major difference from previous work was that the plates spanned the full width of the wind tunnel, i.e. the flow was essentially two-dimensional. The results show major differences from predictions of infinite aspect ratio plates inferred from finite aspect ratio tests as given by Iversen (1979). Moreover, they give excellent correlation with the two-dimensional numerical solution of Lugt (1980) for a 10% thick plate. In contrast to previous results which indicate no autorotation for square cylinders (t/c = 1.0), it is found that autorotation is easily achieved. A new result is that tipspeed ratios are found to be independent of thickness ratio, at approximately the Lugt value over the full range of thickness ratios. Drag coefficients are found to be independent of thickness ratio. There appears to be a critical thickness ratio above and below which the lift coefficients are constant, but are of different magnitude.

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41

Roy, A., and G. Bandyopadhyay. "Numerical calculation of separated flow past square and rectangular cylinders using panel technique." Aeronautical Journal 110, no. 1106 (April 2006): 249–56. http://dx.doi.org/10.1017/s0001924000001226.

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AbstractIn the present investigation, a potential flow model based on panel method has been developed for calculation of two dimensional separated flows past square and rectangular cylinders. Free vortex lines are assumed to emanate from the points of separation that converge downstream of the body. The converged wake shape is iteratively obtained by integrating the velocity vectors at the collocation points. For solving separated flow past square and rectangular cylinders, four different versions of the solver have been developed for a wide range of incidence, namely, for zero, low, moderate and high angles of incidence. For validation of computed results, experimental investigations have been carried out in a low speed wind tunnel to obtain the surface pressure distribution on square cylinder and rectangular cylinder over a range of angles of incidence. Comparison is reasonably good.

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42

Jamińska, Paulina. "The influence of the wind structure definition in the standard k-ε model of turbulence on the distribution of pressure coefficient on the façades of the prism." Budownictwo i Architektura 10, no. 1 (June 11, 2012): 093–104. http://dx.doi.org/10.35784/bud-arch.2233.

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The paper deals with the influence of the definition of turbulence kinetic energy k and dissipation of turbulence kinetic energy ε on wind pressure coefficient distribution on walls of rectangular model. The investigation includes computer simulations for the four cases of boundary conditions, the most common in the literature. In some analysed cases, the wind structure characteristics used in computations were derived from experimental studies performed in the wind tunnel. The results in the form of pressure coefficients were analyzed on the basis of their relevance to the use in the field of wind engineering. All calculations were performed in ANSYS FLUENT with use of standard k-ε model. The 3D model of the flow around the prism was considered in calculations.

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43

SUZUKI, Masayasu. "Wind Tunnel Experiments and Numerical Analysis of Vortex Sound Generated from Rectangular Cylinders." Wind Engineers, JAWE 39, no. 1 (2014): 32–41. http://dx.doi.org/10.5359/jawe.39.32.

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44

Yokoyama, Kenta, Masahiro WATANABE, and Keiichi HIROAKI. "Flutter analysis and wind-tunnel experiments of coupled rectangular sheets in offset arrangement." Proceedings of the Dynamics & Design Conference 2020 (August 25, 2020): 609. http://dx.doi.org/10.1299/jsmedmc.2020.609.

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45

Gkiolas, Dimitris, Demetri Yiasemides, and Demetri Mathioulakis. "Experimental study of a pitching and plunging wing." Aircraft Engineering and Aerospace Technology 90, no. 7 (October 1, 2018): 1136–44. http://dx.doi.org/10.1108/aeat-01-2017-0049.

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Purpose The complex flow behavior over an oscillating aerodynamic body, e.g. a helicopter rotor blade, a rotating wind turbine blade or the wing of a maneuvering airplane involves combinations of pitching and plunging motions. As the parameters of the problem (Re, St and phase difference between these two motions) vary, a quasi-steady analysis fails to provide realistic results for the aerodynamic response of the moving body, whereas this study aims to provide reliable experimental data. Design/methodology/approach In the present study, a pitching and plunging mechanism was designed and built in a subsonic closed-circuit wind tunnel as well as a rectangular aluminum wing of a 2:1 aspect-ratio with a NACA64-418 airfoil, used in wind turbine blades. To measure the pressure distribution along the wing chord, a number of fast responding transducers were embedded into the mid span wing surface. Simultaneous pressure measurements were conducted along the wing chord for the Reynolds number of 0.85 × 106 for both steady and unsteady cases (pitching and plunging). A flow visualization technique was used to detect the flow separation line under steady conditions. Findings Elevated pressure fluctuations coincide with the flow separation line having been detected through surface flow visualization and flattened pressure distributions appear downstream of the flow separation line. Closed hysteresis loops of the lift coefficient versus angle of attack were measured for combined pitching and plunging motions. Practical implications The experimental data can be used for improvement of unsteady fluid mechanics problem solvers. Originality/value In the present study, a new installation was built allowing the aerodynamic study of oscillating wings performing pitching and plunging motions with prescribed frequencies and phase lags between the two motions. The experimental data can be used for improvement of computational fluid dynamics codes in case that the examined aerodynamic body is oscillating.

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Zhou, Shuai, Yunfeng Zou, Xugang Hua, and Zhipeng Liu. "Comparison of Two-Dimensional and Three- Dimensional Responses for Vortex-Induced Vibrations of a Rectangular Prism." Applied Sciences 10, no. 22 (November 11, 2020): 7996. http://dx.doi.org/10.3390/app10227996.

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The accurate prediction of the amplitudes of vortex-induced vibrations (VIV) is important in wind-resistant design. Wind tunnel tests of scaled section models have been commonly used. However, the amplitude prediction processes were usually inaccurate because of insufficient evaluations of three-dimensional (3D) effects. This study presents experimental measurements of VIV responses in a prototype rectangular prism and its 1:1 two-dimensional section model in smooth flow. The results show that the section model vibrates with the same Reynolds number, equivalent mass, frequency, and damping ratio as those of the prototype prism without scale effects. The VIV amplitudes can be qualitatively and quantitatively measured and analyzed. The measured VIV lock-ins of these two models agree with each other. However, the prototype prism produces a 20% higher maximum amplitude than the section model. Several classical VIV mathematical models are used to validate the wind tunnel test results. This confirms that the 3D coupling effects of the modal shape and the imperfect correlations of excitation forces positively contribute to the maximum amplitude. Based on the section model outcomes, the amplified factor of 1.2 is found to be appropriate for the amplitude prediction of VIV for the present prism, and it can also provide a reference for other structures.

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Srinivas, G., and B. P. Madhu Gowda. "Aerodynamic Performance Comparison of Airfoils by Varying Angle of Attack Using Fluent and Gambit." Applied Mechanics and Materials 592-594 (July 2014): 1889–96. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.1889.

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Any aircraft wing is the major component which will play vital role in the generation of lift and at different maneuvering moments throughout the flight. So to maintain this good maneuverability the aircraft wing has to undergo deferent deflections called angle of attack such that the high lift and low drag or vice versa can be settled in the flight. Taking this as the motivation the analysis was carried out on the standard wing airfoil comparing with new designed airfoil. Analyze the numerical simulation values like coefficient of lift, coefficient of Drag, Lift, Drag, and Energy parameters with wind tunnel data to predict accuracy for both the airfoils. Through the selected public literature standard airfoil data and designed airfoil data has been chosen, the geometry was created in the GAMBIT and also the meshing by selecting the suitable c-grid and rectangular grid for the better flow analysis in the FLUENT. The mesh file was imported into the FLUENT software there suitable boundary conditions and operating conditions are given for successful flow convergence. Finally analyzing these results are expecting to be best suitable for good aeromechanical features.

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48

Yoo, Seong-Yeon, Jong-Hark Park, Chang-Hwan Chung, and Moon-Ki Chung. "An Experimental Study on Heat/Mass Transfer From a Rectangular Cylinder." Journal of Heat Transfer 125, no. 6 (November 19, 2003): 1163–69. http://dx.doi.org/10.1115/1.1603780.

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Local and average mass transfer rates from a rectangular cylinder having various width to height ratios are measured using naphthalene sublimation technique, and influence of flow characteristics on mass transfer is investigated. The experimental apparatus comprises a wind tunnel, a naphthalene casting facility and a sublimation depth measurement system. Mass transfer data are compared with those of heat transfer which are obtained using thermocouples in the constant heat flux boundary condition, and analogy between heat and mass transfer is examined. The reasons for discrepancy in both transport values are explained in detail.

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BRUCE, P. J. K., D. M. F. BURTON, N. A. TITCHENER, and H. BABINSKY. "Corner effect and separation in transonic channel flows." Journal of Fluid Mechanics 679 (May 31, 2011): 247–62. http://dx.doi.org/10.1017/jfm.2011.135.

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An investigation into parameters affecting separation in normal shock wave/boundary layer interactions (SBLIs) has been conducted. It has been shown that the effective aspect ratio of an experimental facility (defined as δ*/tunnel width) is a critical factor in determining when shock-induced separation will occur. Experiments examining M∞ = 1.4 and 1.5 normal shock waves in a wind tunnel with a small rectangular cross-section have been performed and show that a link exists between the extent of shock-induced separation on the tunnel centre-line and the size of corner-flow separations. In tests where the corner-flows were modified ahead of the shock (through suction and vortex generators), the extent of separation around the tunnel centre-line was seen to vary significantly. These observations are attributed to the way corner flows modify the three-dimensional shock-structure and the impact this has on the magnitude of the adverse pressure gradient experienced by the tunnel wall boundary layers.

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Ganesan, Surendar, and Balasubramanian Esakki. "Computational fluid dynamic analysis of an unmanned amphibious aerial vehicle for drag reduction." International Journal of Intelligent Unmanned Systems 8, no. 3 (April 17, 2020): 187–200. http://dx.doi.org/10.1108/ijius-01-2019-0003.

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PurposeThe aim of this article is to minimize the drag of an unmanned amphibious aerial vehicle (UAAV) and enhancing the endurance.Design/methodology/approachVarious surface geometrical profiles such as rectangular, semicircular groove, razor blade and V-groove riblets are incorporated into the UAAV, and computational fluid dynamic (CFD) analysis is performed for various angles of attack at diverse vehicle speed conditions to estimate the coefficient of drag considering k–e turbulence model. Comparative evaluation between riblet and blunt body shape methodology is performed. Wind tunnel experiments are conducted to validate the flow characteristics around the UAAV.FindingsIt is observed that V-groove riblet method produced minimal drag in comparison with other profiles. The pressure distributions around UAAV for various geometrical profiles suggested that V-groove profile has achieved minimal vortex region, flow separation and turbulent boundary layer near to the outer profile.Originality/valueThe CFD analysis of UAAV for various riblet configurations and validation with wind tunnel smoke test confirms that UAAV with V-groove riblet provides low drag.

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Journal articles on the topic 'Rectangular wind tunnels'

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