关键词: 多级液力透平；瞬变工况；内部流动特性；数值模拟

Abstract: In order to study the internal flow characteristics of a multistage hydraulic turbine under transient conditions, a two-stage centrifugal pump reversing hydraulic turbine is taken as the research object, and large eddy simulation turbulence model considering the dynamic sublattice stress mode of nonlinear velocity gradient and helix is constructed, considering the nonlinear velocity gradient and helicity, construct the dynamic subgrid stress mode of large vortex turbulence model, the simulation of the variation of the instantaneous pressure pulse, and analyze the transient condition. The results show that under transient conditions, flow transients can cause sudden changes in pressure pulsation of various components inside the hydraulic turbine, and the sudden pressure intensity far exceeds the amplitude of the pressure pulsation of the components inside the hydraulic turbine itself, in which the inlet chamber is most affected by the flow transient, and the impeller is relatively less affected by the flow transient. When the hydraulic turbine is under transient conditions, the velocity streamline distribution of the inlet chamber is more uniform, and the velocity streamline distribution at the impeller becomes relatively uniform, but the velocity streamline distribution at the interstage guide vanes and the outlet chamber is relatively chaotic where are more vortices. The research results will provide a theoretical basis for the improvement of hydraulic turbine structure in the fields of hydrogen energy storage of new energy vehicles and petrochemical industry.

Key words: Multistage hydraulic turbine; Transient conditions; Internal flow characteristics; Numerical simulation