Aerodynamics and Aeroacoustics Investigation of a Low Speed Subsonic Jet

Abstract

Low and high speed subsonic jets have been studied in the last 50 years mainly due its large application in industry, such as the discharge of turbojets and turbofan engines. The purpose of this work is to investigate the aerodynamics and the acoustic noise generated by a single stream jet flow operating at low Mach number 0.25 and Reynolds number of 2,1  105. The main focus is the flow and acoustics characterization of this low speed jet by appling different experimental techniques for evaluating the velocity field via measurements with pitot tube and hot-wire anemometry and farfield noise acquisition by free field microphones. In order to verify the validity of aeroacoustics prediction for such low speed jet, a Computational Fluid Dynamics by means of RANS simulations via k- SST model have been employed coupled with a statistically low-cost Lighthill-Ray-Tracing method in order to numerically predict the acoustic noise spectrum. Sound pressure level as a function of frequency is contructed from the experiments and compared with the noise calculations from the acoustic modeling. The numerical results for the acoustic and flow fields were well compared with the experimental data, showing that this low-cost flow-acoustic methodology can be used to predict acoustic noise of subsonic jet flows, even at low speeds.