Experimental Investigation on the Velocity Field of Wake Flow Around Two Plates in Tandem by LDA

The trailing vortex shedding from the plate cascades is the main factor to introduce vibration and noise of the hydraulic machinery. In this paper, a pair of plate cascades in tandem is taken as the research object. In order to analyze the velocity distribution of the flow and the frequency of the vortex shedding around the plate cascades, the experiments were carried out by LDV measuring system under Re=5000 & 10000. Experimental results show that at the same Reynolds number, the velocity distribution in the center line of the flat wake area can be divided into three regions: reverse flow region, rapid growth region and slow growth region. The existence of the downstream plate significantly suppresses the development of the upstream plate wake and reduces the stream-wise length of the recirculation zone. When the Reynolds number increases from 5000 to 10000, the stream-wise length of the recirculation zone becomes shorter, while the lowest velocity distribution increases. The frequency of the vortex shedding is also reduced from the plate cascades in tandem, and the upper and downstream plate have the same vortex shedding frequency. © 2018, Science Press. All right reserved.