진동하는 날개의 Tip Vortex Roll-up 에 관한 실험적 연구 II: 와도 및 순환

Abstract

An experimental study was carried out to examine quantitatively the tip vortex roll-up in the near-field of an oscillating wing. A NACA 0012 rectangular planform wing with an aspect ratio of 4.0 was mounted on the floor of the wind tunnel test section, and the wing was sinusoidally pitched about the quarter chord. Both the mean incidence angle and the amplitude of oscillation were set at 15º, which makes the angle of attack vary from 0º to 30º. Owing to the large angle of attack, the oscillating wing undergoes a massively separated flow regime. Measurements by using the triple hot-film probe were made for the case of the reduced frequency, K=0.09, and the chord Reynolds number of 3.4x104. The phase-averaged vorticity, turbulence intensity profiles in the wing tip vortex roll-up region are presented and variations of these with respect to the instantaneous angle of attack are discussed in detail. Phase-lag compensated variation of the circulation of the tip vortex during the cycle of oscillation is also included.