Characteristics and analysis of a turbulent offset jet including the effect of density and offset height

Abstract

This paper presents the results of measurements and numerical predictions of 3D turbulent offset jet flows. Mean velocity and turbulence characteristics of a rectangular offset jet with different offset heights and within variable densities are experimentally and numerically investigated in detail. Four jet gas exit densities, ρj = 1.2, 1.25, 1.3 and 1.4 Kg/m3, and four offset ratios, h/w = 8, 16, 25 and 33, are studied. The considered variation of the jet density is revealed at different Reynolds numbers and the velocity measurements are carried out using a Laser Doppler Velocimetry (LDV) technique. The handled configuration is numerically simulated by solving the Navier-Stokes equations with the finite volume method having a non-uniform grid system. Two different closure models are tested: the standard k–ε model and the Reynolds Stress Model (RSM). Results clearly revealed significant effects of the jet density and the offset height on the flow development in the early region. It is noted that the centerline velocity decay increases as the jet density and the offset height increase. It is also observed that the reattachment length of the jet decreases with the increase of the jet density. However, the reattachment length is found to increase with the increase of the offset height.