Flow Around an Object Projected from a Cavity into a Supersonic Freestream

The pressure and flow field of a supersonic flow over a cavity, with and without a store, was the focus of this experiment. One cavity geometry (length to depth ratio 3.6) was studied; the freestream Mach number and the placement of the store relative to the cavity floor were varied. The pressure spectra on the cavity floor were markedly different between Mach numbers of 1.8 and 2.9. The Mach 1.8 case exhibited clear spectral peaks consistent with predictions by Rossiter, whereas the Mach 2.9 flow did not. With the store placed within the free shear layer, the pressure fluctuations on the cavity floor decreased for Mach 1.8 and increased for Mach 2.9. High-speed Schlieren photography was used to visualize the interaction of the free shear layer and the modeled store. Images revealed that flow structures in the free shear layer of the Mach 2.9 flow exhibited less spanwise coherence then their Mach 1.8 flow counterparts. Images also revealed vertical displacement of the free shear layer as the store traversed through it. Pressure-sensitive paint (PSP) was utilized to quantify the full-field mean pressure on the cavity floor and store. A pressure rise near the trailing edge was noted for both freestream Mach numbers. The mean pressure contour of the floor for the Mach 1.8 exhibited considerable three-dimensionality, despite the generally spanwise coherent structures in the free shear layer. (4 tables, 33 figures, 37 refs.)Air Force Inst of Tech Wright-Patterson AFB OH School of Engineering and Management is the author of 'Flow Around an Object Projected from a Cavity into a Supersonic Freestream', published 2004 under ISBN 9781423516583 and ISBN 1423516583.