Application of Potential Theory for the Design of Radial Guide Vanes of Impeller Pumps

Guide vanes of radial impeller pumps possess a large influence on the efficiency, operating range and behaviour. Therefore, their design is crucial and should be based on fluidmechanical models to ensure an optimized and controlled design. In the present contribution a design procedure for guide vanes is described and applied. The design procedure is based on conformal mapping, i.e. a 2D-potential flow of a cascade plane is mapped into the mid-plane of the radial guide vanes. Martensen method is applied to calculate the flow in the cascade plane. By this procedure radial guide vanes are designed and the corresponding 3D-flow in a whole radial impeller pump is modelled by transient CFD-simulations. The CFD results are compared with CFD-data of the flow in an impeller pump with conventional guide vanes. All parts of both impeller pumps (inflow, impeller, etc.) are identical, except the radial guide vanes. The comparison includes the dimensional static pressure increase and total pressure loss over the guide vanes in dependence of volume flow rate as well as the performance curves (head and efficiency versus volume flow rate). Total and static pressure distributions in the mid-plane of the guide vanes are shown and discussed. It is pointed out that the flow of the guide vanes designed by conformal mapping are more homogeneous than the flow in the impeller pump with conventional guide vanes. A comparison of the performance curves of both pumps show that the impeller pump with guide vanes designed by conformal mapping is superior to the impeller pump with conventional guide vanes.