Author(s): Manfred Sallaberger; Andreas Sebestyen; Eberhard Mannschreck; Wolfgang Pinkas
Linked Author(s):
Keywords: Computational Fluid Dynamics; Pump-Impeller; Coupled Computation; Stage-Computation; Navier-Stokes; Cavitation; Pumped Storage Plant; StoragePumps
Abstract: In upgrading of large pumps for increasing the capacity and the efficiency of pumped storage schemes, the design of the new impeller must be matched with the existing, mostly non-optimal, casing. In pumps with suction-elbows of complex shape the interaction of the flow between the suction-elbow and the runner is of great importance. The turn of the flow in the bend of the suction-elbow gives rise to a considerable variation of the flow at runner inlet. Modern coupled computations of both suction-elbow and impeller take these effects into consideration. The investigation of the flow in the impeller and the suction-elbow by using a viscous, three-dimensional computational method is presented. An advanced design scheme is established and its application to two different projects is shown. A check of the mechanical properties by means of a Finite-Element Method is also included in this scheme. Some details of the flow analysis are presented. The variation of the meridional-and the circumferential velocity in the region prior to the runner entry is presented. As a result, the blade profile at runner inlet can be better adapted to the flow and the static pressure distribution on the blade surface is improved. The flow inside the runner channel is visualized by means of streak lines and the qualitative improvement of the flow in a new runner design is pointed out. The application of the new methods results in an improvement both in hydraulic performance and in cavitation behaviour.
Year: 1999