Hydraulic analogy study of supersonic rectangular-jet screech control with cylinders

An investigation into the control of the screech noise of two-dimensional underexpanded supersonic jets was carried out using the hydraulic analogy. Favorable agreement was found with previous experiments between the variations with pressure ratio of the measured screech-amplitude variation and the screech frequency. Remarkably, the intensity of the screech tone was able to be altered substantially by the positioning of a relatively small cylinder along the centerline of the jet flow. Two different cylinder diameters and two different Froude (Mach) numbers were tested. The normalized change in screech-tone intensity for all cases was found to correlate with the relative position in the shock cell of the intersection of the cylinder bow wave and the jet shear layer.