Unsteady numerical simulation of a round jet with impinging microjets for noise suppression

Abstract

The objective of this study was to determine the feasibility of an LBM-LES methodology for the prediction of noise radiation from a round jet-microjet combination. The distinct advantage of LBM over traditional computational fluid dynamics (CFD) methods is its ease of handling problems with complex geometries. A preliminary simulation of an isothermal Mach 0.5, ReD= 1×105 round jet (Dj =0:0508 m) with and without the presence of 18 microjets (Dmj =1 mm). The results revealed a decrease in the axial turbulence intensities and turbulent kinetic energy when the microjets were employed. The reduced intensities translated in a decrease of slightly more than 1 dB in the far-field computed using the porous FfwocsWilliams-Hawkings (FWH) surface integral acoustic method. The trend obtained is in qualitative agreement with experimental observations. This study supports the viability of LBM for microjet applications. Copyright © 2010 by P. Lew, A. Najafiyazdi and L. Mongeau.