Dynamic Pressure Measurements in a Rectangular Cavity with Multiple Stores

Abstract

An experimental investigation is carried out to study the effects of Mach number on the acoustic resonance characteristics of a rectangular cavity with and without multiple stores. Measurements are conducted for a cavity with a length-to-depth ratio of 4.5 at Mach numbers of 2, 3, 4, and 5. Dynamic pressures are measured within the cavity and on the store surfaces. An increase in Mach number results in a decrease in overall sound pressure levels at all measurement locations within the cavity. Pressure spectra indicate that increasing the Mach number decreases both the peak and broadband amplitudes of the cavity pressure fluctuations. At Mach 5, the amplitude of the cavity modes is significantly reduced in the upstream half of the cavity, and the modes are either indistinguishable from broadband levels or absent in the downstream half. The addition of stores reduces cavity acoustics, with two stores offering greater reduction than a single store. The effect of Mach number and the presence of stores on the aeroacoustic feedback loop in a cavity align with literature. Additionally, the pressure fluctuations on the windward store surface scale with Mach number in a similar trend as the cavity acoustics.