scholarly journals Experimental investigation on flow structures of steadily translating low-aspect-ratio wings in low Reynolds number flow

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Yichen Zhu ◽  
Jinjun Wang
Keyword(s):  
Aspect Ratio ◽  
Experimental Studies ◽  
Micro Air Vehicles ◽  
Flow Structures ◽  
3D Flow ◽  
Long Distance ◽  
Reynolds Number Flow ◽  
Low Aspect Ratio ◽  
Number Flow ◽  
Drag Ratio

In recent decades, Micro Air Vehicles (MAVs) have been a hot topic for their promising future. But the promotions of MAVs are hindered by their short endurances. To solve this problem, inspirations are brought from migratory butterflies who utilize the ‘flapping-gliding’ skill during long-distance migration to improve the flight efficiency. The butterfly’s gliding flights, which can be simplified by considering the steadily translating fixed wings, have drawn high attentions. Previous studies mainly focus on the aerodynamics of the low-aspect-ratio fixed wings at Re ≈ 105 via force measurements. However, few experimental studies have measured the 3D flow fields. Consequently, the underlying high lift-to-drag ratio mechanisms in the steadily translating butterfly-shaped wings are still not clear. To shed new light on this problem, the 3D flow structures around butterfly-shaped wings were captured and investigated in detail.

Three-Dimensional Simulation of Micro Air Vehicles with Low-Aspect-Ratio Wings

2007 ◽  
Vol 339 ◽  
pp. 377-381
Author(s):  
Xiao Quan Zhang ◽  
L. Tian
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Wind Tunnel ◽  
Aspect Ratio ◽  
Low Reynolds Number ◽  
Three Dimensional ◽  
Micro Air Vehicles ◽  
Wind Tunnel Experiments ◽  
Low Aspect Ratio ◽  
Dimensional Simulation

Micro Air Vehicles (MAVs) are catching more and more attentions for their broad application in civilian and military fields. Since the theories on the aerodynamics of low Reynolds number are not maturely presented and the wind-tunnel experiments cost long periods and great expenses. The numerical simulation based on computational fluid dynamics (CFD) is a good method to choose. Through three-dimensional simulation of the wings, the aerodynamic characteristics of the flows around MAVs can be easily obtained. The tip vortices produced around low-Reynolds-number and low-aspect-ratio wings can increase the lift and stall angles. The result of numerical simulation can be used as references of theory analysis and wind-tunnel experiments.

scholarly journals WIND TUNNEL CALIBRATION, CORRECTIONS AND EXPERIMENTAL VALIDATION FOR FIXED-WING MICRO AIR VEHICLES MEASUREMENTS

Aviation ◽  
2020 ◽  
Vol 23 (4) ◽  
pp. 104-113
Author(s):  
Ahmed Aboelezz ◽  
Yunes Elqudsi ◽  
Mostafa Hassanalian ◽  
Ahmed Desoki
Keyword(s):  
Reynolds Number ◽  
Wind Tunnel ◽  
Aspect Ratio ◽  
Low Reynolds Number ◽  
Micro Air Vehicles ◽  
Measured Data ◽  
Published Data ◽  
Low Aspect Ratio ◽  
Low Reynolds ◽  
Air Vehicles

The increase in the number of Unmanned Aerial Vehicles (UAVs) and Micro Air Vehicles (MAVs), which are used in a variety of applications has led to a surge in low Reynolds number aerodynamics research. Flow around fixedwing MAVs has an unusual behavior due to its low aspect ratio and operates at low Reynolds number, which demanded to upgrade the used wind tunnel for this study. This upgrade enables measuring the small aerodynamics forces and moment of fixed-wing MAVs. The wind tunnel used in this work is upgraded with a state of art data acquisition system to deal with the different sensors signals in the wind tunnel. For accurate measurements, the sting balance, angle sensor, and airspeed sensor are calibrated. For validation purposes, an experiment is made on a low aspect ratio flat plate wing at low Reynolds number, and the measured data are corrected and compared with published results. The procedure presented in this paper for the first time gave a detailed and complete guide for upgrading and calibrating old wind tunnel, all the required corrections to correct the measured data was presented, the turbulence level correction new technique presented in this paper could be used to estimate the flow turbulence effect on the measured data and correct the measured data against published data.

EFFECT OF ASPECT RATIO ON PRESSURE LOSS AND CHARACTERISTICS OF LOW REYNOLDS NUMBER FLOW THROUGH NARROW SLOTS

2017 ◽  
Author(s):  
Yishak Abdulhafiz Yusuf ◽  
Aleksey Baldygin ◽  
Reza Sabbagh ◽  
Michael Leitch ◽  
Prashant R. Waghmare ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Pressure Loss ◽  
Low Reynolds Number ◽  
Low Reynolds Number Flow ◽  
Reynolds Number Flow ◽  
Number Flow ◽  
Flow Through ◽  
Low Reynolds

Tip Flow Fields in a Low Aspect Ratio Transonic Compressor

1995 ◽  
Author(s):  
P. Russler ◽  
D. Rabe ◽  
B. Cybyk ◽  
C. Hah
Keyword(s):  
Shock Wave ◽  
Aspect Ratio ◽  
Flow Field ◽  
High Frequency ◽  
High Performance ◽  
Flow Structures ◽  
Transonic Compressor ◽  
Low Aspect Ratio ◽  
Laser Data ◽  
Blade Tip

Experimental data and computational predictions are used to characterize the tip flow field of a high performance, low aspect ratio, transonic compressor. Flow structures near the first stage blade tip are monitored experimentally using two different data acquisition schemes. High frequency pressure and laser fringe anemometry data are used to experimentally define the tip flow structure. The high frequency pressure data were acquired with an array of pressure transducers mounted in the rotor casing. Laser data were acquired through a window in the same position. The transducer and laser data adequately define the shock structure at the tip. Both the movement of the shock wave in the blade passage during changes in compressor loading and the interaction between the shock wave and the tip leakage vortex are detected. Similar flow structures and compressor loading effects are numerically predicted using a three-dimensional Navier-Stokes algorithm. A fundamental understanding of the flow field at the blade tip is obtained using these three complementary methods.

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