Numerical analysis of flow structure and entropy production in a rotor-stator cavity under different leakage flow rates

Abstract

Disk friction loss is remarkably significant in low specific speed centrifugal pumps, originating from the complex flow interference within the rotor-stator cavity. To reveal the hydrodynamic mechanism and energy dissipation characteristics of this loss, this study investigates the flow in the rotor-stator cavity under leakage flow conditions by combining experimental measurements with numerical simulations using the Shear Stress Transport (SST) k–ω turbulence model. Furthermore, Entropy Production Theory is introduced to quantify the spatial distribution of energy losses. The results indicate that a typical toroidal vortex structure exists within the cavity, and its morphological evolution directly governs the circumferential velocity in the potential core. Entropy production analysis further reveals that the energy dissipation is primarily composed of mean flow viscous dissipation near the walls and turbulent dissipation within the vortex core region. This study elucidates the loss mechanism of clearance flow from a thermodynamic perspective, providing a theoretical reference for the drag reduction design of low specific speed pumps.