Unsteady Flowfield and Torque Predictions During the Rotation of the Guidevanes of Hydraulic Turbine

Abstract

In the present work, the numerical prediction of the steady as well as of the unsteady flowfield through the cascade of guidevanes of a reaction turbine is examined. The unsteadiness of the flow results from the rotation of the guidevanes around their pivot. The applied numerical procedure is based on the coupling of the boundary element and the vortex particle method and is supplemented by two different procedures for the evaluation of the viscous-inviscid interaction and the boundary layers developed on the vanes. The cinematic conditions at every point of the flowfield are calculated first; however, special attention is paid to the prediction of the torque acting on the cascade and, namely, the variation of the torque during the rotation of the guidevanes, as compared with the torque corresponding to the steady state.