Aerodynamic Design And Optimization Of Radial Inflow Turbine Impeller

Radial inflow turbine achieves high power and high efficiency at low flow ratesand high speeds。It is widely used in vehicles，ships and aviation for its compactstructure, light weight and low cost. However, due to its small channel radius andlarge blade airfoil twist, three-dimensional flow is much obvious and the effect of theviscous force is much significant. The separated vortex is induced inside the flowchannel.Compared with the axial flow turbine, the radial inflow turbine efficiency isstill lower.During its aerodynamic design, further potential has to be explored toimprove its performance. The key research for the radial inflow turbine is to focus onthe aerodynamic optimization design.In this paper, aerodynamic optimization design is mainly carried out for radialinflow turbine impeller as follows:(1)According to the performance requirements, one-dimensional meanline flowdesign was done to select the design parameters, to form the primary meridionalchannel geometry and the velocity triangle of the impeller, to provide a reasonablepreliminary design of radial inflow turbine for three-dimensional aerodynamicoptimization design.(2)CFD technique is applied to simulate the impeller flow and to get the flowproperties, with assessing the design target.The possible range of the optimalparameters of the impeller profile is determined through comprehensive analysis ofthe performance and internal flow field of the impeller.(3) Bezier polynomial curve is used to parameterize radial turbine impeller. Theshape of the impeller flow channel is controlled by varying the control point locationsof the local impeller lines. Efficiency is chosen as the objective function. Uniformdesign optimization method is used to obtain optimal blades. At design conditions,calculation results show that the efficiency of the optimized impeller researched1percent higher over its original one, with the general performance being improved.(4)The impacts of the axial length and the shroud ratio on the impelleraerodynamic performance is also researched. When choosing smaller shroud-ratio,theflow loss is significantly reduced. Because the two factors are taken into considerationin the comprehensive optimization, the effect of the axial length on the aerodynamicperformance is not yet clear. The result shows that the optimization design method adopted in this paper isfeasible. It can provide essential reference for the aerodynamic optimization design ofradial inflow turbine.