Supersonic Jet Noise from a Conical C-D Nozzle with Forward Flight Effects

Abstract

Flow and far-field noise measurements are taken on a conical ConvergentDivergent nozzle similar to the nozzles employed on high-performance tactical jets. Matching flow and far-field computations are presented, produced by Large Eddy Simulation and the Kirchhoff integral method. The conditions examined are those in which the nozzle is operated at its design Mach number of 1.56 while forward flight is simulated at Mach numbers of 0.1, 0.3 and 0.8. Both measurement and LES show that increasing forward flight Mach number to the high subsonic range shortens the initial shock cell size, and weakens the shock cells induced by the nozzle throat relative to the shock cells induced by the nozzle lip. LES shows that high forward flight speed substantially reduces the noise radiated into the forward quadrant where shock noise is dominant. It also removes the screech tone entirely.