Effect of sound-absorbing materials on intensity of disturbances in the shock layer on a flat plate aligned at an angle of attack

Results of a numerical and experimental study of characteristics of disturbances in a hypersonic shock layer on a flat plate covered by a sound-absorbing coating and aligned at an angle of attack are presented. Experiments and computations are performed for the free-stream Mach number $\mathrm{M}_\infty=21$ and Reynolds number $\operatorname{Re}_L = 6\cdot10^4$. A possibility of suppressing pressure fluctuations in the shock layer at frequencies of $20$–$40$ kHz with the use of tubular and porous materials incorporated into the plate surface is demonstrated. Results of numerical simulations are found to be in good agreement with experimental data.