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 to their many applications in industry, such as the discharge of turbojets and turbofan engines. The purpose of this work is to investigate the aerodynamics and the acoustical 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 acoustical characterization of this low speed jet by applying different experimental techniques for evaluating the velocity field by using measurements with a Pitot tube, hot-wire anemometry, and farfield noise acquisition by free field microphones. In order to verify the validity of aeroacoustic predictions for such a low speed jet, a Computational Fluid Dynamics by means of RANS simulations via k-ω SST model have been employed coupled with a statistically low-cost Lighthill-Ray-Tracing method in order to numerically predict the acoustic noise spectrum. The 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 acoustics and flow fields were well compared with the experimental data, thus showing that this low-cost flow-acoustic methodology can be used to predict the acoustic noise of subsonic jet flows, even at low speeds.