Pressure Oscillations from Cavities with Ramp

Study on supersonic flow over wall mounted cavities with different ramp angles is carried out experimentally. Unsteady pressure measurements were made on the walls and floor of the cavity. Data analysis was performed on the experimental results using statistical methods. In the case of cavities with higher ramp angles, high amplitude tones were observed and the presence of an upstream traveling acoustic wave could be confirmed. Cavity with ramp angle of 45 degrees is found to reduce the amplitude of oscillations and the presence of acoustic wave inside the cavity was not detected. Increase in amplitudes has been observed from cavities with ramp angle 30 and 15 degrees. The presence of wave system having velocity greater than acoustic velocity was detected in cavity with 30 degree ramp angle while no presence of acoustic wave was detected in the case of cavity with ramp angle of 15 degrees. The reasons for this ambiguous behavior could not be ascertained. Temporal mode switching occurring in cavities with higher ramp angles was confirmed by spectrogram studies.