Investigation of synthetic jets influence on noise level and its spectral properties for off-design supersonic jet by RANS/ILES method

Abstract

Hybrid Reynolds-Averaged Navier-Stokes/Implicit Large Eddy Simulation (RANS/ILES) highresolution method was applied to investigate synthetic jets influence on potential core length and noise level in supersonic underexpanded jet from converging-diverging nozzle. In this work, temperature and pressure of ambient air were as follows: P ¼ 100 kPa, T ¼ 300 K. Nozzle pressure ratio was NPR ¼ 4 and total temperature at the nozzle inlet was T Ã in ¼ 300 K. Investigation of the accuracy of simulation was carried out before the investigation of synthetic jet influence. Synthetic jets were simulated using approximate boundary condition. Synthetic jets were injected from eight rectangular slits inside nozzle with step of 45 in azimuthal direction. The long sides of the slits were oriented along the longitudinal axis of the nozzle. The amplitude and frequency range of synthetic jets were as follows: q ¼ 50.200 m/s, f ¼ 60.300 Hz. Simulation results showed that the application of synthetic jets noticeably reduces the potential core length. Reducing the potential core length by 24% was achieved on one of the considered operating modes. An explanation for the mechanism of the action of synthetic jets on mixing layer of main jet flow was proposed. Synthetic jets influence on overall sound pressure and narrowband noise was revealed in near and far field. Operating modes, which decrease screech level on several observation angles, were found.