Redesign of an Adjustable Slope Moving Ground Plane Wind Tunnel

2011 ◽  
Author(s):  
Matthew T. Boots ◽  
Meagan L. Hubbell ◽  
Gerald M. Angle ◽  
Emily D. Pertl ◽  
James E. Smith
Keyword(s):  
Wind Tunnel ◽  
Test Section ◽  
Ground Plane ◽  
Ground Effect ◽  
The Body ◽  
Original Design ◽  
Local Pressure ◽  
Maximum Angle ◽  
Close Proximity ◽  
Base Structure

Ground effect is an aerodynamic phenomenon that occurs when moving bodies come in close proximity to the ground. A “cushion” of air is created underneath the moving body which provides additional lift by increasing the local pressure under the body surface. To experimentally test ground effect vehicles, a unique wind tunnel is currently being redesigned and constructed at West Virginia University. This wind tunnel incorporates a rotating belt as the ground plane and a centrifugal fan that generates the air flow through the test section in the same direction as the belt’s rotation. The combination of a rotating belt and airflow is used to mimic ground effect in that it is representative of a body moving through still air in close proximity to the ground. The test section and fan assembly sit on a platform that is connected to a movable base frame. The base and testing platform connect through a pivot point that is capable of being raised upward to a maximum angle of fifty degrees to account for gravitational vector alignment between modeled and real world conditions. When the platform is raised and the belt is spinning, the structure is less stable and has the potential to create errors in force readings due to these oscillations, as well as the potential to tip in extreme wind conditions. Thus, the evaluation of the original design and the subsequent redesign are addressed in this research effort. To stabilize the wind tunnel, additional structural elements have been added downstream of the test section. Two telescoping poles were added to the end of the platform that will connect onto outriggers attached to the base structure. These poles and outriggers will form an A-shape support system when the platform is raised to any degree between zero and fifty. The width of the outriggers was calculated and then modeled in conjunction with the existing base structure. The final design is presented in this paper.

scholarly journals Wind tunnel for studies of latent heat storage

2018 ◽  
Vol 180 ◽  
pp. 02108 ◽  
Author(s):  
Václav Tesař
Keyword(s):  
Wind Tunnel ◽  
Test Section ◽  
Air Flow ◽  
The Body ◽  
Whole Body ◽  
Latent Heat Storage ◽  
Hot Air ◽  
Cold Room ◽  
Solidification Processes ◽  
Sudden Decrease

When a heated solid body temperature reaches the melting point, temperature stops increasing and remains constant until the whole body is completely molten. The heat input during this melting is spent on freeing the body molecules. This latent heat of melting remains inside the body and may be released when the body is cooled and solidifies. This heat was suggested, already several decades ago, for storing thermal energy. The advantage it offers is avoiding high temperature differences - which otherwise decrease effectiveness of storage (by inevitable heat escape by conduction). Also the mass of the body needed to store a given amount of heat is much smaller. For investigations of the melting and solidification processes a special wind tunnel has been designed and is being built in this study. The tested sample of phase change material, encapsulated in a spherical shell, will be exposed in the tunnel to recirculating hot air flow in a 140 mm x 140 mm test section. Sudden decrease in air flow temperature is made by shifting away the whole closed-circuit part of the tunnel and exposing the test section to flow of cold (room temperature) air.

scholarly journals Aerodynamics of an aerofoil in transonic ground effect: Methods for blowdown windtunnel scale testing

2012 ◽  
Vol 116 (1180) ◽  
pp. 599-620 ◽  
Author(s):  
G. Doig ◽  
T. J. Barber ◽  
A. J. Neely ◽  
D. D. Myre
Keyword(s):  
Wind Tunnel ◽  
Ground Plane ◽  
Ground Effect ◽  
Mirror Image ◽  
Navier Stokes ◽  
Oncoming Flow ◽  
Ground Clearance ◽  
Mach Numbers ◽  
Reynolds Averaged Navier Stokes ◽  
Symmetry Method

Abstract Experimental aerodynamic testing of objects in close ground proximity at high subsonic Mach numbers is difficult due to the construction of a transonic moving ground being largely unfeasible. Two simple, passive methods have been evaluated for their suitability for such testing in a small blowdown wind tunnel: an elevated ground plane, and a symmetry (or mirror-image) approach. The methods were examined using an unswept wing of RAE2822 section, with experiments and Reynolds-Averaged Navier Stokes CFD used synergistically to determine the relative merits of the techniques. The symmetry method was found to be a superior approximation of a moving ground in all cases, with mild discrepancies observed only at the lowest ground clearance. The elevated ground plane was generally found to influence the oncoming flow and distort the flowfield between the wing and ground, such that the method provided a less-satisfactory match to moving ground simulations compared to the symmetry technique.

scholarly journals Aerodynamics of an aerofoil in transonic ground effect: numerical study at full-scale Reynolds numbers

2012 ◽  
Vol 116 (1178) ◽  
pp. 407-430 ◽  
Author(s):  
G. Doig ◽  
T. J. Barber ◽  
A. J. Neely ◽  
D. D. Myre
Keyword(s):  
Numerical Study ◽  
Ground Plane ◽  
Ground Effect ◽  
Reynolds Numbers ◽  
Lower Surface ◽  
Aerodynamic Performance ◽  
The Body ◽  
Aerodynamic Efficiency ◽  
Critical Mach Number ◽  
Positive Effects

Abstract The potential positive effects of ground proximity on the aerodynamic performance of a wing or aerofoil have long been established, but at transonic speeds the formation of shock waves between the body and the ground plane would have significant consequences. A numerical study of the aerodynamics of an RAE2822 aerofoil section in ground effect flight was conducted at freestream Mach numbers from 0·5 to 0·9, at a range of ground clearances and angles of incidence. It was found that in general the aerofoil’s lifting capability was still improved with decreasing ground clearance up until the point at which a lower surface shock wave formed (most commonly at the lowest clearances). The critical Mach number for the section was reached considerably earlier in ground effect than it would be in freestream, and the buffet boundary was therefore also reached at an earlier stage. The flowfields observed were relatively sensitive to changes in any given variable, and the lower surface shock had a destabilising effect on the pitching characteristics of the wing, indicating that sudden changes in both altitude and attitude would be experienced during sustained transonic flight close to the ground plane. Since ground proximity hastens the lower surface shock formation, no gain in aerodynamic efficiency can be gained by flying in ground effect once that shock is present.

scholarly journals Evaluation of a Textile PIFA for Wearable IoT Application and its Challenges

2021 ◽  
Vol 15 (3) ◽  
pp. 289-302
Author(s):  
Hadi Aliakbarian ◽  
Azadeh Hajiahmadi ◽  
Nordiana Mohamad Saaid ◽  
Ping Jack Soh
Keyword(s):  
Human Body ◽  
Ground Plane ◽  
The Body ◽  
Link Quality ◽  
Test Case ◽  
Antenna Performance ◽  
Textile Antenna ◽  
Close Proximity ◽  
Transceiver Module ◽  
Conductive Textile

The ever increasing use of body-worn systems in the Internet of Things application such as needs better antenna subsystem designs compatible with its requirements. Several challenges limiting the performance of a body-worn system, from materials, and environmental conditions  to the effects of on body application and its hazards are discussed. As a test case, a flexible textile planar inverted-F antenna is presented and discussed. The choice of this topology is due to its simplicity in design and fabrication, relatively broad bandwidth and the presence of a rear ground plane, which minimizes the impacts of the human body on the antenna performance. It is designed on a felt substrate, whereas Aaronia-shield conductive textile is utilized as its  conductive parts (radiator, shorting wall and ground plane). The antenna performance are studied in two cases, first in free space and then in bent conditions in the close proximity to the human body. The influence of the relative humidity on the textile antenna performance is also investigated numerically. Simulated and measured results indicated good agreements. Finally, the proposed antenna is integrated with a transceiver module and evaluated on the body in practice. Its wireless link quality is assessed in an indoor laboratory.

Simulation and Analysis on Pressure Resistance Experiments of Automotive Body

2012 ◽  
Vol 490-495 ◽  
pp. 1451-1455
Author(s):  
Guang Yao Zhao ◽  
Yi Feng Zhao ◽  
Chuan Yin Tang ◽  
Zhi Yuan Du
Keyword(s):  
Energy Absorption ◽  
The Body ◽  
Original Design ◽  
Element Analysis ◽  
Vehicle Simulation ◽  
Automotive Body ◽  
Safety Regulations ◽  
Vehicle Rollover ◽  
Pressure Resistance ◽  
Body Energy

Aimed at SUV-type vehicle, simulation and analysis of pressure resistance experiments on the body of automobile has been presented in the paper, according to the vehicle safety regulations and standards of FMVSS216. A limited SUV vehicle model is created; simulation is obtained with the help of software LS-DYNA, based on the principle of finite element analysis method. Assessment of pressure resistance and safety of the automobile has been presented, from the aspect of the deformation of body, the energy absorption of the vehicle and components, and the pressure on the body, etc. By rational improving of the original design of body structure, the reasonable distribution of pressure absorbability of the body of the SUV-type automobile is achieved. The effect of the overall energy absorption of the body is fully exerted, and then the safety of the driver and the passenger in a rollover accident is improved. Research methods and conclusions of this paper provide useful ways and references to the research of the safety of vehicle rollover and design of rationality of body energy absorption

Aerodynamic interference test of quad tilt rotor aircraft in wind tunnel

2019 ◽  
Vol 233 (15) ◽  
pp. 5553-5566 ◽  
Author(s):  
Kun Chen ◽  
Zhiwei Shi ◽  
Shengxiang Tong ◽  
Yizhang Dong ◽  
Jie Chen
Keyword(s):  
Wind Tunnel ◽  
Reference Value ◽  
Ground Effect ◽  
Open Loop ◽  
Force Balance ◽  
Scale Model ◽  
Operating Condition ◽  
Tilt Rotor ◽  
Interference Test ◽  
Aerodynamic Interference

There is an obvious aerodynamic interference problem that occurs for a quad tilt rotor in near-ground hovering or in the conversion operating condition. This paper presents an aerodynamic interference test of the quad tilt rotor in a wind tunnel. A 1:35 scale model of the quad tilt rotor is used in this test. To substitute for the ground, a moveable platform is designed in a low-speed open-loop wind tunnel to simulate different flight altitudes of the quad tilt rotor in hovering or forward flight. A rod six-component force balance is used to measure the loads on the aircraft, and the flow field below the airframe is captured using particle image velocimetry. The experimental results show that the ground effect is significant when the hover height above the ground is less than the rotor diameter of the quad tilt rotor aircraft, and the maximum upload of the airframe is approximately 12% of the total vertical thrust with the appearance of obvious fountain flow. During the conversion operating condition, the upload of the airframe is reduced compared with that in the hovering state, which is affected by rotor wake and incoming flow. The aerodynamic interference test results of the quad tilt rotor aircraft have important reference value in power system selection, control system design, and carrying capacity improvement with the advantage of ground effect.

Aerodynamics of a Fixed Ground Plane for a Powered STOL Wind-Tunnel Model

1973 ◽  
Vol 10 (3) ◽  
pp. 137-142
Author(s):  
J. E. Hackett ◽  
J. L. Justice
Keyword(s):  
Wind Tunnel ◽  
Ground Plane ◽  
Wind Tunnel Model ◽  
Tunnel Model

scholarly journals Hovering performance of Anna's hummingbirds ( Calypte anna ) in ground effect

2014 ◽  
Vol 11 (98) ◽  
pp. 20140505 ◽  
Author(s):  
Erica J. Kim ◽  
Marta Wolf ◽  
Victor Manuel Ortega-Jimenez ◽  
Stanley H. Cheng ◽  
Robert Dudley
Keyword(s):  
Wing Length ◽  
Ground Effect ◽  
The Body ◽  
Plane Angle ◽  
Metabolic Power ◽  
Wingbeat Frequency ◽  
Body Angle ◽  
Induced Flow ◽  
Induced Velocity ◽  
Calypte Anna

Aerodynamic performance and energetic savings for flight in ground effect are theoretically maximized during hovering, but have never been directly measured for flying animals. We evaluated flight kinematics, metabolic rates and induced flow velocities for Anna's hummingbirds hovering at heights (relative to wing length R = 5.5 cm) of 0.7 R , 0.9 R , 1.1 R , 1.7 R , 2.2 R and 8 R above a solid surface. Flight at heights less than or equal to 1.1 R resulted in significant reductions in the body angle, tail angle, anatomical stroke plane angle, wake-induced velocity, and mechanical and metabolic power expenditures when compared with flight at the control height of 8 R . By contrast, stroke plane angle relative to horizontal, wingbeat amplitude and wingbeat frequency were unexpectedly independent of height from ground. Qualitative smoke visualizations suggest that each wing generates a vortex ring during both down- and upstroke. These rings expand upon reaching the ground and present a complex turbulent interaction below the bird's body. Nonetheless, hovering near surfaces results in substantial energetic benefits for hummingbirds, and by inference for all volant taxa that either feed at flowers or otherwise fly close to plant or other surfaces.

Sign in / Sign up

Export Citation Format

Share Document