Numerical study of features propagation of acoustic disturbances in unregulated supersonic air intake

With the help of the «Vortex&Wawe Tracker» program, a number of calculations were carried out to identify the peculiarities of the propagation of acoustic disturbances in the channel of a supersonic air intake with a high level of flow inhomogeneity and turbulence. The problems for a cylindrical channel with a uniform flow and a selected unregulated air intake were considered. We used productions with and without vortex-resolving approach, with and without fan perturbations. By plotting phase velocity diagrams and comparing the results of different calculations, acoustic disturbances generated by the flow and propagation fan disturbances were separated and considered. The work contains descriptions of the features of each of the components. Calculations have shown a weak influence of intense turbulence on the rate of attenuation of fan disturbances and a strong influence on their structure, including a change in frequency. It is noted that the rapid transformation of the initial structure of disturbances should affect the operation of sound-absorbing structures and the process of noise shielding by airframe elements. It should be noted that the flow in a practically acceptable air intake will be more homogeneous and less turbulent, which requires additional calculations before generalizing the conclusions.