A Study of Swirling Backflow and Vortex Structure at the Inlet of an Inducer

This paper describes a vortex structure at the inlet of an inducer which appears on the boundary of backflow region. The vortex structure was visualized by the cavitation voids found by operating at cavitation number of σ=0.050 and recorded by a high speed video. It was measured quantitatively by two laser displacement sensors. The passing frequency and the shape of vortex filaments were determined from the outputs of the laser displacement sensors which respond to the passage of the vortex cavitation. The results show that the number of vortex filaments, their propagation angular velocity and radial location depend on the steady velocity profile at the inlet.