Frequencies of Transverse and Longitudinal Oscillations in Supersonic Cavity Flows

Abstract EN

A supersonic flow over a rectangular cavity is known to oscillate at certain predominant frequencies.

The present study focuses on the effect of the cavity length-to-depth ( L / D ) ratio on the frequency for a free-stream Mach number of 1.7.

The pressure oscillations are measured by changing the L / D ratio from 0.5 to 3.0, and the power spectral density is calculated from the temporal pressure signals for each L / D ratio.

The results demonstrate that the spectral peaks for an L / D ratio of less than ~1 and greater than ~2 are accounted for by the feedback mechanisms of the transverse and longitudinal oscillations, respectively.

The results also demonstrate that the spectral peaks in the transition (1 <~ L / D <~ 2) are accounted for by either of the two feedback mechanisms of transverse and longitudinal oscillations; that is, the flows under the transition regime oscillate both transversely and longitudinally.