Abstract
This paper presents results of an experimental study on incompressible turbulent flow over a rectangular cavity. The experiment was carried out to clarify the strength and three-dimensional nature of cavity oscillations for fully turbulent inflow. Particle image velocimetry (PIV) and fluctuating pressure measurements were made in a closed, re-circulating water tunnel for cavity length-depth ratio from L/D=1 to 4 at a momentum thickness based Reynolds number, Reθ=8,300. Measured power spectra of pressure fluctuations show dominant frequencies with broad peak width indicating the absence of resonant oscillations. Pressure fluctuations at two spanwise separated locations are well correlated at the frequency range in which dominant peaks are found. Instantaneous flow fields reveal strong three-dimensional distortions. Although formation and passage of turbulent eddies are observed in the instantaneous x (streamwise)-y (vertical) plane flow field, instantaneous x-z (spanwise) plane flow fields show strong spanwise variations.
