遷音速ディフューザ流れにおける衝撃波の自励振動 : (第1報, 衝撃波を揺らすじょう乱の発生源と振動機構)

抄録

Mechanism of self-excited shock oscillation in two-dimensional transonic diffuser flow is investigated experimentally. The diffuser used in this work is composed of the flat top wall and the curved bottom wall. Time-sequence of shock location is recorded by the high speed CCD camera combined with schlieren system, together with simultaneous measurements of static pressure fluctuations along the top wall. The pressure fluctuations at many locations on the side wall are also measured simultaneously. As a result, it is found that disturbances which induce shock oscillation are propagating upstream from downstream portion of the shock wave where the boundary layer behaves unsteadily and the most violently. Furthermore, vortices generated by the shock oscillation are observed to be convected downstream. The shock oscillation is explained to be sustained by the upstream-propagating disturbances and the downstream-convected vortices.