A214 ヘリカル振動する超音速ジェットから放射されるスクリーチ・トーンの音源について

概要

論文の詳細を見る
Underexpanded jets issuing from convergent circular nozzle are known to radiate a powerful acoustic tone called screech. The steady decreases of the screech frequency with increasing pressure ratio is interrupted by four frequency jumps as the mode of jet instability changes successively from two axially symmetric ones A_1 and A_2,a lateral one B, a helical one C, and a lateral one D. The frequency of helical mode C is significantly higher than that of the adjacent lateral modes. In the present experimental study, the sound sources in the helical oscillation mode was investigated by using a series of the instantaneous sch lieren photographs. From the photographs, it is confirmed that the sound source for the dominant helical oscillation mode C is the prominent point which moves along a circular orbit in the plane perpendicular to the jet axis and just downstream the rear edge of the third shock cell. The Doppler shifted frequency of the sound accompanying the moving sound source was detected.
日本流体力学会の論文
2000-07-25