Influence of sound-absorbing coatings on the development of disturbances in a flowing mixture of vibrationally excited gases

Abstract

In the present paper, we study the development of disturbances on a solid (continuous) plate and on a plate covered with a sound-absorbing coating, both installed at an angle of attack in a hypersonic flow (M_∞ = 8.44) of a vibrationally excited mixture of carbon dioxide with nitrogen. The rms fluctuations of pressure were measured on the surface of the plates in a short-duration IT-302M wind tunnel of ITAM SB RAS. The numerical simulation was performed on the basis of solving the two-dimensional unsteady Navier-Stokes equations and a two-temperature model of relaxation flows. In modeling a real porous coating, a skeletal model was used. The model is formed by square elements arranged in staggered order with a distance between elements equal to the diameter of the pores in the sound-absorbing material used in the experiment. Data on the dynamics of the disturbance development on the solid plate and on the plate with the sound-absorbing coating under different conditions of the incident flow are reported. The effect of various parameters of the sound-absorbing coating (depth, length, and location on the plate) was studied. It is shown that the sound-absorbing coating significantly (up to 50 %) suppresses the intensity of pressure fluctuations on the plate surface as compared with the solid surface. A good agreement between the calculated and experimental data on the pressure pulsations on the surface of the plates is demonstrated.