scholarly journals Impact of thermal gradients on wind tunnel force measurements

1999 ◽  
Author(s):  
James Hereford ◽  
Peter Parker
Keyword(s):  
Wind Tunnel ◽  
Thermal Gradients ◽  
Force Measurements

scholarly journals A wind-tunnel case study: Increasing road cycling velocity by adopting an aerodynamically improved sprint position

2019 ◽  
pp. 175433711986696
Author(s):  
Timothy Crouch ◽  
Paolo Menaspà ◽  
Nathan Barry ◽  
Nicholas Brown ◽  
Mark C Thompson ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Drag Coefficient ◽  
Aerodynamic Drag ◽  
Time Trial ◽  
Force Measurements ◽  
Sampling Errors ◽  
Repeated Testing ◽  
Road Cycling ◽  
Wind Tunnel Study

The main aim of this study was to evaluate the potential to reduce the aerodynamic drag by studying road sprint cyclists’ positions. A male and a female professional road cyclist participated in this wind-tunnel study. Aerodynamic drag measurements are presented for a total of five out-of-seat sprinting positions for each of the athletes under representative competition conditions. The largest reduction in aerodynamic drag measured for each athlete relative to their standard sprinting positions varied between 17% and 27%. The majority of this reduction in aerodynamic drag could be accounted for by changes in the athlete’s projected frontal area. The largest variation in repeat drag coefficient area measurements of out-of-seat sprint positions was 5%, significantly higher than the typical <0.5% observed for repeated testing of time-trial cycling positions. The majority of variation in repeated drag coefficient area measurements was attributed to reproducibility of position and sampling errors associated with time-averaged force measurements of large fluctuating forces.

An Historical and Applied Aerodynamic Study of the Wright Brothers’ Wind Tunnel Test Program and Application to Successful Manned Flight

2005 ◽  
Author(s):  
Michael G. Dodson ◽  
David S. Miklosovic
Keyword(s):  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Scaling Effects ◽  
Force Measurements ◽  
Velocity Gradients ◽  
Tunnel Model ◽  
Image Velocimetry ◽  
Manned Flight ◽  
Flow Quality ◽  
Scale Design

A replica wind tunnel was built and used to test the flow quality through the Wright Brothers’ wind tunnel. The research determined the effect flow quality and experimental method had on the Brothers’ results, and whether those results were useful in a quantitative sense. Particle image velocimetry revealed boundary layers extending 2.5” (63.5 mm) from each wall, and velocity gradients as large as 20% along the wind tunnel model span resulting in an asymmetric lift distribution. Similarly, the balance generated asymmetric wingtip vortices contributing to asymmetric downwash along the span of the model. Direct force measurements of a replica of the Wrights #12 airfoil showed their lift measurements were at least 7% and as much as 15% too low, and numerical analysis revealed wind tunnel predictions for lift, drag, and efficiency were not applicable to full scale design due to Reynolds number scaling effects.

A New Support Structure in Waverider Force Measurement

2013 ◽  
Vol 318 ◽  
pp. 96-99
Author(s):  
Xue Jun Zhao ◽  
Xiao Guo Guo ◽  
Chang Zhao
Keyword(s):  
Wind Tunnel ◽  
Force Measurement ◽  
Test Results ◽  
Force Measurements ◽  
Support Structure ◽  
Inlet Flow ◽  
Hypersonic Wind Tunnel ◽  
Vehicle Aerodynamics ◽  
Set Up ◽  
Opening And Closing

In this paper a new support structure was given to solve the problem met in the force measurement with engine jet. The force measurements of waverider were undertaken in the hypersonic wind tunnel. The test condition was at Ma=6, angle of attack α=-6°-6°, at which we researched the effects on the vehicle aerodynamics of inlet cowl opening and closing, support system, engine jet, and pressure ratios. To decrease the effects of strut on the jet flow-field, we took sharp belly strut to support the model in the wind tunnel. The belly strut could support the waverider model, force measurement balance, and it could make the inlet flow set up, and provide the high pressure jet. The test results showed that the belly sharp strut had little effects on the flowfield and could inject the inlet flow, and could provide very high quality jet.

Comparison of Wind Tunnel and Full-Scale Aerodynamic Sail Force Measurements

2002 ◽  
Author(s):  
Heikki Hansen ◽  
◽  
Peter Jackson ◽  
Karsten Hochkirch ◽  
◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Full Scale ◽  
Force Measurements

Wind-tunnel Force-measurements of Gurney Flaps for Active Control of Wind Turbine Blades

2022 ◽  
Author(s):  
Wasi U. Ahmed ◽  
Keshav Panthi ◽  
Giacomo Valerio Iungo ◽  
D. Todd Griffith ◽  
Mario Rotea ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Wind Turbine ◽  
Active Control ◽  
Turbine Blades ◽  
Force Measurements ◽  
Wind Turbine Blades ◽  
Gurney Flaps

scholarly journals Flow Angularity Investigations in an Automotive Slotted Wall Wind Tunnel

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4575
Author(s):  
Emil Ljungskog ◽  
Simone Sebben ◽  
Alexander Broniewicz
Keyword(s):  
Heat Exchanger ◽  
Wind Tunnel ◽  
Test Section ◽  
Vortical Flow ◽  
Settling Chamber ◽  
Force Measurements ◽  
Volvo Cars ◽  
Before And After ◽  
Ground System ◽  
Induced Flow

The Volvo Cars aerodynamic wind tunnel has had a vortical flow angularity pattern in the test section since its original commissioning in 1986. The vortical flow nature persisted after an upgrade in 2006, when the fan was replaced and a moving ground system was introduced. It has been hypothesized that the cause for this flow angularity pattern was leakages around the heat exchanger installed in the settling chamber. The present paper tests this hypothesis by measuring the flow angularity in the test section before and after sealing the leakages. The findings show that the leakage path around the heat exchanger does not influence the flow angularity, and that the current pattern is different compared to the commissioning after the upgrade. This prompted an investigation of the influence from the turbulence screens, which were changed after the upgrade commissioning. These investigations indicate that the probable cause of the vortical flow angularity pattern is residual swirl from the fan. Force measurements on a reference car with and without extra induced flow angularity show that the flow angles measured in the tunnel for regular operation are most likely small enough to not have a significant effect on the measured aerodynamic forces.

Aerodynamic force measurements of the smooth surface ball and baseball ball by wind tunnel experiment

2003 ◽  
Vol 2003.56 (0) ◽  
pp. 141-142 ◽  
Author(s):  
Masashi UCHIMURA ◽  
Taketo MIZOTA ◽  
Yasunori NAKAMURA ◽  
Tomohiro OKAYAMA
Keyword(s):  
Wind Tunnel ◽  
Smooth Surface ◽  
Aerodynamic Force ◽  
Wind Tunnel Experiment ◽  
Force Measurements

Wake Structure of Typical Automobile Shapes

1981 ◽  
Vol 103 (1) ◽  
pp. 162-169 ◽  
Author(s):  
S. R. Ahmed
Keyword(s):  
Wind Tunnel ◽  
Kinetic Energy ◽  
Flow Visualization ◽  
Rotational Motion ◽  
Separation Bubble ◽  
Force Measurements ◽  
Wake Structure ◽  
Subsequent Formation ◽  
Longitudinal Vortices ◽  
Scale Models

The time averaged wake structure of three characteristic vehicle shapes viz. Estate, Fastback and Notchback was studied on the basis of flow visualization and wake surveys behind smooth quarter scale models in a wind tunnel. The models differed through their upper rear-end shape. Flow in the separation bubble at vehicle base and the subsequent formation of a pair of longitudinal vortices aft of this region is analysed. The kinetic energy of the rotational motion in the wake is evaluated to give a “vortex drag” rating for the vehicle shapes investigated. Effect of body details was assessed by a parallel set of experiments with detail models of same principal dimensions. Force measurements supplemented the investigations.

A Critical Re-Evaluation of Hydrodynamic Theories and Experiments in Subcavitating Hydrofoil Flutter

1966 ◽  
Vol 10 (02) ◽  
pp. 122-132
Author(s):  
Wen-Hwa Chu
Keyword(s):  
Wind Tunnel ◽  
Experimental Research ◽  
Hydrodynamic Theory ◽  
Force Measurements ◽  
Surface Theory ◽  
Towing Tank ◽  
Force Calculation ◽  
Possible Cause ◽  
Theory And Experiments ◽  
Classical Hydrodynamic

A review of relevant hydrodynamic information has been made, with emphasis on the possible cause of serious discrepancies between classical hydrodynamic theory and experiments for subcavitating hydrofoils. The usefulness of the best available wind tunnel and towing tank force measurements is also discussed. It is believed that these data are unreliable, and that the completion of the force calculation based on the classical lifting surface theory and subsequent flutter prediction for an actual flutter model is desirable. Some recommendations for possible future experimental research are also given.

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