Analysis of jet instability in flute-like instruments by means of image processing : effect of the channel geometry on the jet instability

We are studying experimentally the behavior of jets in flute-like instruments. At the time being most models for jet oscillations are based on linear jet instability analysis described by Rayleigh. But there is no clear model for the initial perturbations induced by transverse acoustic velocity. Aiming to understand and describe the origin of the perturbation, we are currently investigating the jet motion under transverse acoustic perturbation generated by loudspeakers. The jet behavior is analyzed through flow visualization and image processing using a crosscorrelation technique. The paper will present results for different flue channel geometries. The linear instability is investigated. Experimental results are compared to a theoretical linear model.