Jet Noise Abatement Using Elliptical Ring Tabs

Aero-acoustic characteristics of a high-speed jet with elliptical ring tabs fitted at the aft of the nozzle in diametrically opposite to the exit is experimentally investigated at a Mach Number of 1.8. The Main focus is to examine the effects of the extent of elliptical ring tabs, its position in the mixing layer and also to study the characteristics of supersonic nozzle with and without elliptical ring tabs. The elliptical ring tabs are found to produce vortices, thereby increasing the surface area of the jet, particularly in the close vicinity of the nozzle, which increases the mixing and reduces the potential core length. The overall noise levels registered along the jet edge immediately downstream of the nozzles are higher, but further downstream they are reduced in comparison with the plain baseline nozzle. A pair of dimensionally optimized elliptical ring tab placed diametrically opposite at the exit of the nozzle with blockage area of 5% without effecting the loss of thrust. The mixing enhancement caused by the tab will be studied at nozzle pressure ratio 5.75. The reduction in Sound Pressure Level (SPL) in dB is compared to that of plain nozzle.