Numerical study on unidirectional fluid–solid coupling of Francis turbine runner

Abstract

To analyze the fluid–solid coupling stress characteristics of the Francis turbine runner comprehensively, based on the Reynolds-averaged Navier–Stokes equations and shear stress transport k-ω turbulence model, this article performs numerical simulation of three-dimensional steady incompressible turbulent flow through the whole passage of a certain large Francis turbine under multiple operating conditions with Computational Fluid Dynamic software CFX and contrasts the result with that model test conversion. With the help of ANSYS workbench platform, equivalent stress, deformation distribution, and variation of the runner under multiple operating conditions are obtained through loading the water pressure on the runner blade as structural plane load to blades by the method of unidirectional fluid–solid coupling. The results show that under small flow operating conditions, flow patterns in the runner are disordered, the stress on the blade distributes unevenly, and the maximum stress lies on the influent side of the blades connected to the band; as the flow increases, the stress appears intensively around the effluent side of the blades connected to the runner crown. The maximum deformation first decreases and then increases as the flow increases. The deformation area expands from the middle effluent side of blades to the band. The results can be found in the researches on the structure design and the safety and stability of the Francis turbine runner.