Analyzing the Impact of the Inlet Temperature on the Acoustic Noise Production from a Supersonic Jet using LES

Non-ideal expanded supersonic jets emerging from a nozzle produce three different types of noise, i.e., shock-associated broadband noise,screech noise, and the turbulent mixing noise. The screech tone occurs due to self-excitation in a feedback-loop of flow propagating downstream and acoustic wave interaction. In downscaled laboratory experiments often the screech noise occurs, while the real applied exhaustjet of a gas turbine engine does not show this phenomena. Apart from a geometric scaling difference, usually a lower temperature is employed in experimental studies. The compressible Navier-Stokes equations are simulated numerically by a large eddy simulation approach to investigate the effect of jet operation temperature onto the noise development in a supersonic jet originating from a convergent-divergent nozzle. The jet-exit Mach-number is 1.56, while the total temperature ratios are 1.27, 2.46, and 3.65. The differences in the acoustic near-field will be presented and the interaction of flow-field with acoustic waves will be analyzed and compared to each other.