Shock-Tracking Procedure for Studying Screech-Induced Oscillations

摘要

A pattern-tracking procedure has been developed to follow shock oscillations in a jet plume under screech condition. This procedure includes treatment of the raw schlieren images and the use of an existing pattern-matching algorithm. Near-field pressure measurements have also been performed in order to link screech properties to shock oscillations. The following have been consistently observed: 1) The oscillation frequency of shocks is equal to that of screech. 2) The mode of oscillation of shocks, symmetric or antisymmetric, is the same as the screech mode. 3) The motion magnitude is an increasing function of the screech amplitude. 4) The relation between screech amplitude and shock oscillation magnitude is peculiar to each screech mode.