For the geometry of the nozzle blade and the rotor blade of theradial inflow turbine, the single passage model is established by CFD,and the numerical simulation of the flow field in the turbine is carriedout. The structure of the nozzle and rotor is optimized by studying theflow characteristics and aerodynamic properties of the turbine.In consideration of the symmetry of the position between the nozzleblades, the flow conditions of the working fluid in the nozzle passageare basically the same. In order to obtain the calculation results, thesingle passage model of the nozzle is used for numerical calculation andresearch. The geometric model and structured grid of the blade areshown in Fig. 9.The geometrical structure, physical parameters and flow characteristics of the rotor are characterized by distinct periodicity. TheBoolean operation is used to obtain the fluid region in the rotor. Therotor structural body and the fluid domain are shown in Fig. 10(a) and(b), respectively.In the meshing process, following components are divided moredensely by the O-grid method, such as the rotor blade near wall surface,the blade leading edge boundary and the blade trailing edge boundary,so that y+ is about 3. According to the design parameters, mesh segmentationand mesh generation are performed on the flow passage. Thestructured grid of the rotor is shown in Fig. 11(a). Fig. 11(b) is a partiallyenlarged view of the leading edge of the rotor passage. Additionalgrid treatment is implemented and a detailed simulation is conductedfor its flow field, so that the calculation accuracy can be effectivelyimproved.