WALL JET DEVELOPMENT IN A TURBULENT RECIRCULATING CAVITY FLOW

A turbulent wall jet within a confining recirculating cavity was examined using flow visualization, particle image velocimetry (PIV), and laser Doppler velocimetry (LDV). The PIV technique was used macroscopically for flow visualization as well as at a much finer resolution to determine detailed velocities within the developing wall jet. Comparison data collected using laser Doppler velocimetry (LDV) was used for validation purposes. The wall jet was well characterized using conventional unbounded wall jet parameters. Wall jet velocity profiles collapsed onto a single profile with the application of the appropriate parameters, indicating some degree of similarity after the initial jet region and up to the mid wall distance. Distances past this region were characterized by a rapid decay in the jet caused by the adverse pressure gradient created by the bounding wall. It was found that the wall jet growth rate within the recirculating cavity was greater than that of an unbounded wall jet in a stagnant fluid. This phenomenon is attributed to the recirculating flow, confining boundaries, and the initial jet exit velocity conditions.