On the Effects of Wind Tunnel Floor Tangential Blowing on the Aerodynamic Forces of Passenger Vehicles

2017 ◽  
Vol 10 (2) ◽  
pp. 591-599 ◽  
Author(s):  
Emil Ljungskog ◽  
Simone Sebben ◽  
Alexander Broniewicz ◽  
Christoffer Landström
Keyword(s):  
Wind Tunnel ◽  
Aerodynamic Forces ◽  
Passenger Vehicles ◽  
Tunnel Floor ◽  
Tangential Blowing

Extremely Gusty Winds from a Viewpoint of Aerodynamic Force

2020 ◽  
Author(s):  
Junji Maeda ◽  
Takashi Takeuchi ◽  
Eriko Tomokiyo ◽  
Yukio Tamura
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Rise Time ◽  
Aerodynamic Force ◽  
Step Function ◽  
Object Size ◽  
Aerodynamic Forces ◽  
Wind Force ◽  
Wind Observation

To quantitatively investigate a gusty wind from the viewpoint of aerodynamic forces, a wind tunnel that can control the rise time of a step-function-like gust was devised and utilized. When the non-dimensional rise time, which is calculated using the rise time of the gusty wind, the wind speed, and the size of an object, is less than a certain value, the wind force is greater than under the corresponding steady wind. Therefore, this wind force is called the “overshoot wind force” for objects the size of orbital vehicles in an actual wind observation. The finding of the overshoot wind force requires a condition of the wind speed recording specification and depends on the object size and the gusty wind speed.

Model Test Techniques Developed to Investigate the Wind Heeling Characteristics of Sailing Vessels and Their Response to Gusts

1991 ◽  
Author(s):  
Barry Deakin
Keyword(s):  
Wind Tunnel ◽  
Model Test ◽  
Wind Tunnels ◽  
Stability Assessment ◽  
Tunnel Floor ◽  
The Stability ◽  
Scaled Models ◽  
Scale Data ◽  
Heeling Moment ◽  
Gust Response

During the development of new stability regulations for the U.K. Department of Transport, doubt was cast over many of the assumptions made when assessing the stability of sailing vessels. In order to investigate the traditional methods a programme of work was undertaken including wind tunnel tests and full scale data acquisition. The work resulted in a much improved understanding of the behaviour of sailing vessels and indeed indicated that the conventional methods of stability assessment are invalid, the rules now applied in the U.K. being very different to those in use elsewhere. The paper concentrates on the model test techniques which were developed specifically for this project but which will have implications to other vessel types. The tests were of two kinds: measurement of the wind forces and moments on a sailing vessel; and investigation of the response of sailing vessels to gusts of wind. For the force and moment measurements models were mounted in a tank of water on a six component balance and tested in a large boundary layer wind tunnel. Previous tests in wind tunnels have always concentrated on performance and the heeling moments have not normally been measured correctly. As the measurements of heeling moment at a range of heel angles was of prime importance a new balance and mounting system was developed which enabled the above water part of the vessel to be modelled correctly, the underwater part to be unaffected by the wind, and the interface to be correctly represented without interference. Various effects were investigated including rig type, sheeting, heading, heel angle and wind gradient. The gust response tests were conducted with Froude scaled models floating in a pond set in the wind tunnel floor. A mechanism was installed in the tunnel which enabled gusts of various characteristics to be generated, and the roll response of the models was measured with a gyroscope. These tests provided information on the effects of inertia, damping, rolling and the characteristics of the gust. Sample results are presented to illustrate the uses to which these techniques have been put.

Flight Characteristics of Flapping Wing Miniature Air Vehicles With “Figure-8” Spherical Motion

2009 ◽  
Author(s):  
Mohamed B. Trabia ◽  
Woosoon Yim ◽  
Zohaib Rehmat ◽  
Jesse Roll
Keyword(s):  
Mathematical Model ◽  
Wind Tunnel ◽  
Experimental Testing ◽  
Flapping Wing ◽  
Dynamic Stall ◽  
Wind Tunnel Testing ◽  
Servo Motor ◽  
Aerodynamic Forces ◽  
Flapping Motion ◽  
Spherical Motion

Hummingbirds and some insects exhibit “Figure-8” flapping motion that allows them to go through a variety of maneuvers including hovering. Understanding the flight characteristics of Figure-8 flapping motion can potentially yield the foundation of flapping wing UAVs that can experience similar maneuverability. In this paper, a mathematical model of the dynamic and aerodynamic forces associated with Figure-8 motion generated by a spherical four bar mechanism is developed. For validation, a FWMAV prototype with the wing attached to a coupler point and driven by a DC servo motor is created for experimental testing. Wind tunnel testing is conducted to determine the coefficients of flight and the effects of dynamic stall. The wing is driven at speeds up to 12.25 Hz with results compared to that of the model. The results indicate good correlation between mathematical model and experimental prototype.

scholarly journals Estimation of Aerodynamic Load on Radome Structure Mounted on Top of a Surveillance Aircraft

2020 ◽  
Vol 9 (3) ◽  
pp. 1969-1973
Keyword(s):  
Wind Tunnel ◽  
Pressure Distribution ◽  
Structural Design ◽  
Pressure Transducer ◽  
Dorsal Side ◽  
Aerodynamic Load ◽  
Aerodynamic Forces ◽  
Support Structure ◽  
Aerodynamic Angles ◽  
Valve Pressure

The design and development of radome external structure, requires aerodynamic forces acting on it and its distribution. This paper discusses the wind tunnel studies carried out for estimating the incremental effects due to the installation of large ellipsoidal radome along with the support structure pylons on the dorsal side of the fuselage. Effect of locations of radome at 36 m and 31.5 m from the nose of the fuselage is discussed. Further using the scan-valve pressure transducer, the pressure distribution on the radome measured at different aerodynamic angles required for the structural design of radome structure is also brought out. Flow visualization study which are useful for qualitative check for the effect of installation of the radome with support structure on the effectiveness of the empennage is attempted.

Effects of Cyclist Size and Position Within Formations on Drag and Side Force in the Presence of Cross Winds

2019 ◽  
Author(s):  
Ivaylo Nedyalkov ◽  
Alec Cunningham ◽  
Adam Lovell
Keyword(s):  
Reynolds Number ◽  
Wind Tunnel ◽  
Drag Reduction ◽  
Aerodynamic Forces ◽  
Side Force ◽  
Scale Models ◽  
Force Reduction

Abstract In the absence of cross-winds, a cyclist can expend up to 90% of their energy to overcome drag and can save up to 30% of that energy if riding behind another cyclist. The aerodynamic forces acting on cyclists in the presence of cross wind have not been studied in much detail. The effect of the offset distances between cyclists on the aerodynamic forces has been investigated in the literature for configurations of two cyclists. In the present study, 1:11 scale models of two different cyclists were rapid-prototyped and tested in a wind tunnel. The effect of the size of the cyclist was studied by placing the larger cyclist model behind the smaller one; the smaller behind the larger one; and the larger model behind an identical (larger model) copy. The effect of position within the group was studied by measuring the forces on each of the four cyclists placed in a favorable formation. The results suggest that the size of the cyclist matters, particularly when the leading cyclist is smaller than the drafting cyclist, and the effect is more prominent for the side forces. The results also show that in a formation of four cyclists, the leading cyclist experiences minor drag reduction compared to riding alone. The second and third cyclists experience the largest force reductions within the group, and the fourth cyclist experiences force reduction, which is not as significant. The results appear to be dependent on the Reynolds number, but may still be valuable for racing strategies and recreational cycling.

Wind Tunnel Test of a Blended Wing Aircraft in Ground Effect With Active Flow Control

2016 ◽  
Author(s):  
Michael Mayo ◽  
Jonathan Carroll ◽  
Nicholas Motahari ◽  
Warren Lee ◽  
Robert Englar
Keyword(s):  
Wind Tunnel ◽  
Active Flow Control ◽  
Wind Tunnel Test ◽  
Ground Effect ◽  
Circulation Control ◽  
Wing Model ◽  
Subsonic Wind Tunnel ◽  
Test Methodology ◽  
Tunnel Floor ◽  
Lift And Drag

This paper describes the test methodology and results for a wind tunnel experiment featuring a blended wing aircraft in ground effect with built-in circulation control. A 82.55cm wingspan blended wing model was tested in a subsonic wind tunnel at velocities ranging from 18m/s – 49m/s and corresponding Reynolds numbers ranging from 130k – 350k. Pitch angle was held constant at 0 degrees and the height above the wind tunnel floor was modified to determine lift and drag modification due to ground effect. At a normalized height (y/bw) of 0.06, ground effect increased lift production by 24% and reduced drag by 22% when compared to a normalized height of 0.5. The addition of the circulation control significantly increased the lift production of the model at a cost of increased drag. At a normalized height of 0.031, the lift production increased by 200% at a blowing coefficient of 0.01, but the drag also increased by 72%, ultimately increasing L/D by 178%. Experimental results also suggest that ground effect and circulation control have a synergistic effect when used simultaneously. The effects of Reynolds number and circulation control slot height are also investigated.

Airfoil-Type Separated Boundary Layer Generated on a Wind-Tunnel Floor

2003 ◽  
Author(s):  
Yvan Maciel ◽  
Antoine Vénisse ◽  
Steve Julien ◽  
Jean Lemay
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Tunnel Floor
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