Experimental study of self-sustained oscillations in a confined jet

We present an experimental study of a planar jet confined in a rectangular cavity. In certain geometrical configurations and for sufficiently large Reynolds numbers, this system exhibits self-sustained oscillations characterized by a well-defined wavelength and frequency of die jet. We describe flow regimes observed by varying the Reynolds number and the cavity length. The self-sustained oscillation regime is studied in detail: we extract the fundamental frequency and determine the selection criterion for the wavelength using a method of visualization, which has the advantage of being non intrusive. We show the existence of a band of allowed wavelengths and establish the upper and lower limits for the wavelength selection criterion. We discuss the validity of the visualization method for the measurement of the wavelength and frequency using a simple analytical model of the streaklines.