Characterisation of acoustic field induced by flow past cavities in supersonic combustors

This paper reports about a preliminary investigation on the characteristics of acoustic radiation by a two-dimensional confined supersonic flow past a wall-mounted cavity. Rectangular cavities of nine different L/D ratios were considered: three “deep”, three “shallow'’ and three “square” shapes. Inlet Mach numbers of 1.5 and 2.0 were tested. Results obtained are in the form of (a) acoustic measurements at different locations on the wall of the test section opposite to the cavity wall and (b) visualisation of the flow in and around the cavity. A wide range of acoustic amplitudes was recorded at different locations with different cavities. The results help in the identification of cavity shapes that are most suited for further consideration in future studies on mixing, secondary fuel injection, and combustion. The visualisation experiments suggest more locations corresponding to oscillating shocks where acoustic amplitudes could be larger than recorded so far.