Structure of a Stronger Wall Jet Managed by a Pair of Streamwise Vortex (Behavior of Streamwise Vortex and Distortion of Mean Velocity Field)

摘要

Interaction process between a turbulent plane wall jet and a pair of streamwise vortex was investigated experimentally. Two kinds of vortex pair, i.e., common-flow up and common-flow down generated with half-delta wings mounted on the wall, were introduced into a self-preserving stronger wall jet. Measurements on the mean velocity and mean streamwise vorticity were made to examine deformation and relaxation process of the mean flow field as well as evolution of the streamwise vortex. As a strategy in the present experiment, the vortex center goes into the outer layer in the case of common-flow up and stays in the inner layer in the case of common-flow down. Consequently, streamwise vortex pair interacts strongly with the large-scale eddy governing the entire wall jet. The following remarks were recognized for the common-flow up in comparison with results of both cases ; 1) growth of vortex radius and decay of streamwise vorticity are greater, 2) recovery of the mean velocity field is much slower. The evaluation of streamwise momentum flux confirms that it is possible to manage turbulent wall jet with streamwise vortex.