Supersonic Jet Noise Reduction using Micro Vortex Generators*

A novel technology for jet noise reduction using micro vortex generators is developed and tested

on a laboratory scale model of a supersonic faceted nozzle. Nozzle experiments were conducted at UC Acoustic Test Facility along with NRL simulations using LES, for conditions relevant to tactical aircraft take off conditions in the overexpanded regime. The noise reduction technologies involve introducing streamwise vortices in supersonic nozzle flow to enhance the shear layer mixing and thus affecting the jet’s coherent structures. The vortex generators employed are fin type vortex generators that have the added benefit of altering the shock cell structures to

alter the broad band shock associated Noise. A set of design parameters affecting the level of noise reduction was systematically explored. The high-pressure gradient across the mvgs induces the formation of two counter rotating vortices that caused upwash between each pair and downwash between two neighboring pairs. Nozzle lip separation was delayed due to momentum transfer from the nozzle flow to the boundary layer. Far acoustic field measurement showed substantial reduction of the shock associated noise and mixing noise. The impact of different parameters of the MVG design will be shown.