Experimental study of influence of trailing wall geometry on cavity oscillations in supersonic flow

An experimental study of the supersonic flow over cavities with different trailing wall geometries was carried out at a free stream Mach number of 1.63. All the cavities have same length, depth and length-depth ratio. For two pairs of cavity configurations studied the trailing wall angle is maintained the same. The study involves instantaneous shadowgraph visualization and unsteady pressure measurement. Results indicate that two cavities among those investigated are highly unstable while the others are relatively stable. For the cavities which are unstable four different type of waves are observed in the flow field. SPL and cross-correlation plots indicate high amplitude tones and the presence of forward travelling acoustic wave inside the cavity respectively in these cavities. In the case of cavities which are stable, all the four type of waves which were observed in the flow field of the cavities which are unstable could not be identified. SPL and cross-correlation plots indicate drop in the amplitude of the tones and the absence of acoustic wave inside the cavity respectively in these cavities.