An Investigation on V-Notch Controlled Asymmetric Supersonic Jet

The major disadvantages associated with high-speed aircraft are the larger supersonic core and the intense noise from the supersonic plume ejected from the aircraft exit which can be mitigated by the controlled manipulation of the supersonic jet core. This essentially can be achieved by the introduction of vortex generators at the exit of the supersonic nozzle. The present study investigates the influence of V-notch and plain tabs types of vortex generators, placed at the exit of a supersonic elliptical nozzle, aiming to improve mixing efficiency, reduce the core length, and thereby decrease aeroacoustic noise from the supersonic asymmetric jet. Particularly, the innovative V-notch design has been introduced as it introduces mixed-size mixing promoting vortices due to its unique varying shape from the base, which is effective in jet mixing. The experimental investigations have been conducted in a supersonic jet test facility to analyze the performance of a Mach 1.6 elliptic jet under different nozzle pressure ratios (NPRs). The elliptical nozzle, along with plain tabs and V-Notch, is examined through centerline Pitot pressure measurements, radial Pitot pressure profiles, and Schlieren images. The results from the centerline Pitot pressure distributions demonstrate that the V-notch has a superior capability in reducing potential core length, with reductions of 72.62% at NPR 6, 64% at NPR 4.25, and 62.5% at NPR 2.5 which is much better than the performance with plain tabs. This essentially indicates effective jet mixing due to the ability of V-notch to induce diverse sizes of vortices. Schlieren images further support the superior performance of V-notch in reducing shock cell length compared to plain tabs controlled and uncontrolled jets. Essentially, the varying size of vortices shed from the V-notch are very effective in demonstrating its superior mixing of controlled elliptic jet over plain tab which makes V-notch a promising element for optimizing asymmetric jet flow characteristics in aerospace engineering applications.