VORTEX SHEDDING FROM FIXED AND OSCILLATING RECTANGULAR PRISMS IN SHEAR FLOWS

摘要

The main focus of this paper is to study the results of experiments on six different rectangular prisms with varied side ratios, with and without forced oscillation, displaced in two shear free streams and one uniform flow. The setting of free stream shear parameters P=dU/dyxD/Uc are 0.024 and 0.032. With respect to vortex shedding phenomena, a comparison between shear flows and uniform flows is also part of the focus. Experimental results indicate that disturbance on the two-dimensional vortex shedding of the uniform flow is caused by the longitudinal vortex of the shear flow gradient. As a result, a spanwise distribution of cells among the vortex shedding frequencies is created. Increases in the side ratios of the rectangular prisms can cause a shifting of cell boundaries toward the high-speed end. As shear parameters for the same prism increase, the cell boundaries move toward the low-speed end. During oscillation, differences arise between the vorticity structures of cells, and the vortices of each cell are more unified, with improvements in correlation.