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A bio-inspired device for drag reduction on a three-dimensional model vehicle
Dongri Kim1, Hoon Lee, Wook Yi
1Department of Mechanical & Aerospace Engineering, Seoul National University, Seoul 08826, Korea.
Bioinspiration & Biomimetics
|March 11, 2016
Summary
A novel bio-mimetic device, the automatic moving deflector (AMD), reduces drag on vehicles by mimicking bird feathers. This automatic moving deflector (AMD) technology achieved up to 19% drag reduction by controlling airflow separation.
Area of Science:
- Fluid Dynamics
- Aerodynamics
- Bio-inspired Engineering
Background:
- Vehicle aerodynamics are crucial for fuel efficiency.
- Flow separation on vehicle surfaces, particularly at high angles of attack, significantly increases drag.
- Existing drag reduction methods often lack adaptability to varying flow conditions.
Purpose of the Study:
- To introduce and evaluate a bio-mimetic device, the automatic moving deflector (AMD), for reducing aerodynamic drag on a 3D Ahmed body model.
- To investigate the mechanism of drag reduction by the AMD, inspired by secondary feathers on bird wings.
- To determine the effectiveness of the AMD at a critical 25° slanted surface angle.
Main Methods:
- Wind tunnel experiments were conducted on an Ahmed body with varying automatic moving deflector (AMD) sizes and materials.
- Drag force measurements were taken at Reynolds numbers (Re H) from 1.0 × 10^5 to 3.8 × 10^5.
- Velocity and surface-pressure measurements were used to analyze flow behavior and automatic moving deflector (AMD) operation.
Main Results:
- The automatic moving deflector (AMD) achieved drag reductions of up to 19%.
- Automatic moving deflector (AMD) activation was correlated with pressure differentials between the slanted surface gap and the upper surface of the deflector.
- An empirical formula was derived to predict the critical free-stream velocity for automatic moving deflector (AMD) operation.
Conclusions:
- The automatic moving deflector (AMD) effectively reduces drag by controlling flow separation on the rear slanted surface.
- Drag reduction is primarily due to pressure recovery and suppression of longitudinal vortices.
- The bio-mimetic design offers a promising approach for adaptive drag reduction in vehicles.
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