Wind Tunnel tests (WTT) were conducted measuring time average C_(PRMS) and mean C_p unsteady pressures acting on internal surfaces of rectangular cavities to build an understanding of the flow for free-stream speeds between U_∞ = 30 - 60m/s at Length-to-Depth (L/D) ratios; 0.5,0.8 at D = 380mm and 2 at D = 152mm. Root-Mean Square (RMS) of unsteady pressure C_p was computed to determine oscillatory peaks over variation of U_∞. Increasing length L as L/D = 0.5 - 0.8; showed an increase in intensity at all speeds. Decreasing depth D as L/D = 0.8-2 showed a shift in intensity from the walls to the floor at all speeds. Fluctuations were slightly less periodic from 30 - 60m/s, as increased speed reduced C_(PRMS) along x/L and y/D however increased C_p. Generally, as speed increases a cavities response changes, exhibiting progressively steeper gradients and larger pressure until a maximum respective to geometry. At this point, the cavity alters it's flow field to expel air faster. When mass outflow isn't enough, acoustic waves start to emit, becoming resonant at the onset velocity of the lower limiting frequency. Further work will investigate resonant modes and correlate their presence to the internal flow structure, observing effects of the absolute size and width.
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