EFFECT OF UPSTREAM DISTURBANCE ON JET NOISE AND ITS REDUCTION

In the paper, the effect of upstream disturbance on jet noise is studied. By the experiments, It is found that the effect is mainly due to the upstream noise radiated through the nozzle exit. The weak nonlinear interaction between upstream noise and downstream turbulence is supposed. An empirical formula about the "excess noise" reduced by the micropore muffler is set up, according to experiments.