Friday, April 26, 2013 4:00 p.m. in ETC 4.150
Professor Philip J. Morris
Department of Aerospace Engineering
The Pennsylvania State University
The noise generated by modern tactical fighter aircraft can cause noise-induced hearing loss in personnel located near the aircraft and annoyance in communities surrounding military bases. This is a special problem for the Navy as both landing and takeoff involve high power engine settings and personnel on a carrier deck are located very close to the aircraft. The jet noise generated by the hot supersonic jet exhausts involves two source mechanisms. The dominant noise is turbulent mixing noise generated by the supersonic convection of the large turbulent structures in the jet exhaust. This generates the highest levels and radiates in the downstream arc. The interaction of the turbulence with shock cells in the jet plume results in broadband shock-associated noise. This is important at larger angles to the jet downstream axis. This talk will describe different ways to predict these two noise sources and their radiation. Broadband shock-associated noise is predicted on the basis of an acoustic analogy and steady Reynolds averaged Navier-Stokes simulations. The mixing noise is predicted using unsteady Navier-Stokes simulations coupled to an acoustic analogy for wave extrapolation to a far field observer. Finally, a new method to reduce the strength of these jet noise sources is described. Results of simulations and experiments to demonstrate the effectiveness of this noise reduction method will be given.