F315 螺旋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(F-31 騒音(1),一般講演)

概要

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It is well known that very strong sound waves called screech tone are radiated from supersonic jets. Screech tone is generated by the feedback loop consisting of the downstream-convecting coherent vortical structure around the jet and upstream-propagating sound waves in the ambient. The circular supersonic jet oscillates in several oscillation modes. Recently, we investigated the generation mechanism of the sound sources of the screech tone radiated from the jet oscillating in the helical mode by using schlieren visualization technique. From this experimental study, it is shown that the point sound sources are rotating about the jet axis in the planes perpendicular to the jet axis slightly downstream of the rear edges of the shock cell structure. The speed of the sound sources is supersonic and the envelopes of the moving Mach cones generated behind the sound sources form the helical-shaped wave front of the screech tone.
日本流体力学会の論文
2004-08-09