| Flow past a shallow wall cavity is of great interest for both its fluid dynamic and acoustic properties. The characteristics of the flow are dependent upon the Reynolds number, Mach number and the nature of the boundary layer upstream of the cavity. However, despite numerous investigations into various aspects of the flow, the cavity's fluid dynamic properties have yet to be fully characterized for both laminar and turbulent upstream conditions.; The purpose of this study was to characterize the flow around and within a shallow wall cavity for both a laminar and turbulent upstream boundary layer. Characterization included measurements of the mean velocities and Reynolds stresses upstream, within and downstream of the cavity for both laminar and turbulent upstream boundary layers. The data obtained from this study will be used in the development and validation of computational methods for predicting fluid and acoustic phenomenon associated with this flow field.; The experiments were carried out within a low speed wind tunnel designed specifically for the study of boundary layer flows. The data was obtained using two component hot-wire and. Laser Doppler Velocimeter systems. A microphone and single hot-wire probe were used to investigate the spectral characteristics of the flow in the cavity.; The results highlight the differences in the flow for a laminar and turbulent upstream boundary layer. Analysis of the data shows that the vorticity field for the laminar case is stronger and more localized towards the trailing edge than for the comparable turbulent case with the same freestream velocity, with the maximum vorticity 30% larger for the laminar case. Reynolds Stress measurements reveal differences in both the path and magnitudes of the shear layer for the laminar and turbulent cases, especially near the leading edge of the cavity, where the Reynolds Stresses for the turbulent cases were as much as twice those of the laminar cases. Measurements downstream of the cavity show the separate cases converging towards a common turbulent boundary layer. The cavity was found to be non-resonating, and the criteria necessary for cavity resonance developed from previous experimental investigations was compared to the results obtained here. |
