Numerical Study of the Features of the Propagation of Acoustic Disturbances in an Unregulated Supersonic Air Intake

Using the Vortex and Wave Tracker program, a number of calculations are 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 the selected unregulated air intake are considered. The calculations are performed with and without the vortex-resolving approach, as well as with and without fan disturbances. The acoustic disturbances generated by the flow and the evolving disturbances of the fan are separated and considered by plotting phase velocity diagrams and comparing the results of different calculations. This study contains descriptions of the features of each of the components. The calculations show the weak influence of intense turbulence on the rate of attenuation of the fan disturbances and the 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 the 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.