SHEAR LAYER COUPLING WITH SIDE-BRANCH RESONATORS.

The purpose of this paper is to present experimental results obtained from side branch cavity resonance studies utilizing a three-dimensional junction geometry. The investigation involved studies of cavity sound pressure level as a function of frequency for a variety of cavity depths and main pipe velocities. Flow visualization techniques were employed to reveal the vortex formation process and organization as a function of shear layer mode. The significance of these analyses were two-fold. First, the visualization studies revealed a correlation between the number of vortices simultaneously populating the shear layer and the mode of shear layer instability. Second, the interface geometry studied was unique with respect to similar experimental investigations which in the past have considered two-dimensional junction geometries exclusively.