Using wavelet and Hilbert-Huang transforms for analyzing unsteady pressure fluctuations inside an open-type shallow cavity

Flow over an isolated shallow open-type rectangular cavity was investigated experimentally. Pressure measurements at Mach numbers 0.3, 0.5 and 0.6 were performed. Turbulent boundary layer was naturally developed along a flat plate upstream the cavity. During the experiments two test configurations were employed. Strong resonance was observed in the pressure signals obtained at M = 0.5 and M = 0.6 for the test configuration with the short upstream plate. Instantaneous oscillating characteristics were studied by Wavelet and Hilbert-Huang transforms of pressure signals. The resonant intermittency was observed for a shallow cavity flow.