Numerical study of the surface and subsurface vortices suppression in a rectangular pump basin using anti-vortex devices

The present study reports the results of high-resolution free surface Unsteady Reynolds Averaged Navier-Stokes (URANS) simulations of the three-dimensional (3D) flow field in a rectangular pump intake system. The numerical simulations are composed of various scenarios without/with various anti-vortex devices (AVDs) to suppress the surface and subsurface vortices around the pipe. For this purpose, after performing a comparison between the streamlines of a benchmark test case and the data available in the literature, the 3D vortical structures around the pipe and inside of the basin have been visualized using the Q-criterion. In addition, the circulation and swirl angle indices inside the pipe are implemented for evaluating the performance of different types of AVDs. The results showed that the surface vortices cause low frequency oscillations in the pump inlet. In this case, the use of a curtain wall controls the surface vortices and eliminates low frequency and high amplitude oscillations in the pump inlet. Examining various cases with AVDs shows that none of the scenarios with AVDs could fully control the surface and submerged vortices. Due to this fact, a novel geometry for the pump basin is introduced which suppresses the entire free surface, submerged and floor vortices.