The efficiency of the method of sound-absorbing coatings in vibrationally excited hypersonic flow

We have studied the effect of a porous sound-absorbing insert on the intensity of pressure pulsations in the high-temperature hypersonic flow of carbon dioxide past the surface of a plate oriented at a 10.2$^\circ$ angle of attack. The mode composition of disturbances in the flow core of a pulsed wind tunnel has been experimentally determined, which is dominated by acoustic disturbances of a fast mode. It is established that, under the action of acoustic disturbances of the fast mode on the shock layer, the sound-absorbing insert reduces the intensity of pressure pulsations on the plate surface as compared to a continuous surface. The experimental data are compared to the results of numerical simulations.