Numerical Simulation of Flow Field, Fountain Flow and Associated Noise in Supersonic Impinging Twin Jet using Large Eddy Simulation

Abstract

A three-dimensional flow field is produced by a supersonic twin-jet impingement. It is studied using the turbulence model Large Eddy Simulation (LES). The numerical model consists of two parallel jets of diameter 3D apart, which are issued from a plane which is at a distance H = 2D, 3D, 4D above the ground. The Nozzle Pressure Ratio (NPR) is kept at 3.7 for all the flow conditions.  The study is based on the extent of rise of the fountain due to the impinging of the jets on the ground plane. The associated noise is calculated from the pressure distributions at certain important points defined. Instantaneous flow, mean velocity magnitude, RMS pressure data, mean centre line jet velocities and various fountain flow contours for the twin-jet impingement are produced and discussed. A high level of unsteadiness and strong interactions between the fountain and the jets are observed, which varies for the different H/D ratios.

Keywords: LES, supersonic twin-jet impingement, acoustics, vortex formation, fast fourier transform