Experimental investigation of two-stream mixing flows with streamwise and normal vorticity

This study provides detailed velocity information in the mixing region of two-stream mixing flows wit h streamwise and normal vorticity for the computational fluid dynamics (CFD) methods validation. Three trailing-edge configurations for the dividing mechanism had been considered; namely, a convoluted plate, a robed forced mixer, and a scalloped forced mixer. The first two have been examined previously by visualization tests (Manning 1991). A velocity ratio of 0.6 was generated with initial turbulent boundary layers and was nominally two-dimensional (2-D). Velocity measurements were made on fine cross-plane grids across the wake region and at several streamwise locations using a two-component laser-Doppler anemometer (LDA). The streamwise vortex development for the robe mixer and the scalloped mixer underwent a three-step process by which it was formed, intensified, and quickly dissipated. The shear layer growth rates were rapid for the scalloped mixer and lobed mixer cases from the trailing edge to a point where the streamwise vorticity was almost dissipated. Consequently, the growth rate reduced and became lower than that of the convoluted plate. In the absence of the streamwise vorticity, the growth rate for the convoluted plate relied only on the 2-D roll-up of the normal vorticity. (C) 1997 by Elsevier Science Inc.