Three-dimensional analysis of flow in the spiral casing of a reaction turbine using a differently weighted Petrov Galerkin method

Abstract

A weighted residual based finite element method has been used to predict the flow structure and the head loss in the spiral casing of a reaction turbine. An explicit Eulerian velocity correction scheme has been employed to solve the complete Reynolds-averaged Navier-Stokes equations. A Differently Weighted Petrov Galerkin (DWPG) method has been used for spatial discretization. The simulation has been performed for high Reynolds numbers. The head loss in the spiral casing has been calculated for Re=5×10⁵ and Re=10⁶. The velocity field and the pressure distribution inside the spiral casing corroborate the trends available in literature. The velocity field reveals the existence of a free-vortex character of the global flow field. A strong secondary flow is evolved on the cross-stream plane due to the centrifugal forces which act at right angles to the main flow.