Numerical simulation and experimental study on an innovative vortex eliminator using a modified SST turbulence model for gas-liquid two-phase flow

Abstract

Vortices in the turbine and pump threatens the safe operation of the unit. The purpose of this paper is to design an antivortex guide cone (AVGC) based on the dynamic characteristics of the vortices. A new approach with modified SAS-SST turbulence model was adopted to simulate the vortex, which is verified by model experiments. The velocity gradient is the key factor of vortex generation, so the antivortex device with vortex elimination blades adopt streamline structure to reduce the velocity gradient in vortex area. Three schemes with N0 (N0 is the number of vortex elimination blades) of 4, 6 and 8 are designed respectively. The study results indicate that the vortex elimination effect of AVGC varies greatly with different N0, resulting in great differences in the performance of the unit. Some local small-scale vortices still exist near AVGC in Scheme 1 (N0 = 4). In Scheme 2 (N0 = 6) is 6, vortices can be eliminated thoroughly with the least hydraulic loss and the unit efficiency improved by 1.8%. In Scheme 3 (N0 = 8), some new channel vortex will be generated in the blade channel, resulting in more hydraulic loss. Only the hydraulic loss produced by AVGC less than that produced by vortex that indicate the scheme is feasible. The research work can provide important academic value and engineering insights to eliminate vortex.