Studies on the Transition of the Flow Oscillations over an Axisymmetric Open Cavity Model

Computations and experimental validation were conducted to obtain flow field over an axisymmetric cavity with different front wall inclinations at a freestream Mach number of 2.0. Flow oscillation in and around the cavities may incur a damaging effect on the stable flight of the aircraft and store releases. Aero-acoustic from the oscillating flow induces vibration in the local bay structure and causes structural fatigue. Hence an open cavity of L/D=3 and 5 has been investigated to obtain the flow oscillation pattern and aero-acoustics. Axisymmetric simulation, three-dimensional simulations on axisymmetric bodies were carried out using FLUENT. Further analysis has been done using slanted front wall of axisymmetric cavity model. A comparison has been drawn between the oscillation level for all different cases and theirtransitions has been studied. Experiments involved schlieren, measurement of static and unsteady pressures. Qualitative flow field details obtained through experiments and computations on axisymmetric body have been validated for L/D=3 and are in good agreement. Pressure oscillations and mean surface pressure distribution on the cavity surface have been observed for each cases and the results showed that there is a sharp transition in oscillation pattern while moving from L/D=3 to 5.