Turbulence measurements of an inclined rectangular jet in a boundary layer

Abstract

Turbulence measurements are performed for streamwise vortices induced by a rectangular jet in a turbulent boundary layer, using laser doppler anemometry (LDA)in a wind tunnel experiment. The chapter provides a database for validating numerical models of an inclined rectangular jet in a boundary layer. When properly arranged, the rectangular jet is able to produce a superior vortex for flow control than a round jet at the same mass flow rate. Both turbulent kinetic energy (TKE) and primary shear stress distributions suggest complex flow physics, particularly in the areas around the center of the vortex, and between the vortex and the wall. The TKE is characterized by the wake of the jet and its cross plane distribution is characterized by concentric contors, the peak value of which drops sharply as the vortex develops. Distinct areas of negative and positive values characterize the turbulent production and convection of TKE. A high level of turbulent mixing is found to contribute to the relatively quick drop of the crossplane circulation level .The cross-plane primary shear stress distribution features an area of positive, above the center of the vortex, and an area of negative beneath it. The center of the vortex is found to represent the location of the vortex better than the peak vorticity.