Automatic moving deflector를 이용한 3차원 자동차 모델의 항력 감소

In the present study, we present a bio-mimetic flow control device, AMD (Automatic Moving Deflector), for drag reduction of a three-dimensional model vehicle. The model vehicles considered are GM model (from GM company) and Ahmed body. The GM model is modified such that it contains a slant part at its base. The present bio-mimetic flow control device is inspired by the secondary feathers of a bird wing which passively pop up at landing, and is installed at the critical slant angle of each model, at which the drag coefficient is the highest. The experiment is conducted in a wind tunnel at Re H = 1.3 × 10 5 - 3.8 × 10 5 , based on the model height H. To investigate the drag reduction by the AMD, we measure the drag force on each model vehicle with and without the AMD. With the present AMD, the drag coefficient is decreased by up to 7% and 20% on the GM model and the Ahmed body, respectively. To investigate the mechanism of the drag reduction by the AMD, we measure the wall-pressure at the slant surface and the vertical base of each model. We also measure the velocity field around each model using particle image velocimetry. The wall-pressure and velocity measurements indicate that the drag reduction by AMD results from the separation delay caused by the AMD.