Investigation On Aerodynamic Design And Optimization Method For Radial Turbine

Radial turbine, as a small heat-work conversion unit, is widely used in different fields. Radial turbine, for example, is the key component of small gas turbines and the application areas of such gas turbines include distributed power generation, combined heat and power supply, subsidiary power generation of military vehicle and so on. This dissertation investigates the radial turbine one-dimensional aero-thermal preliminary design,3D modeling and the aerodynamic optimization method. The main contents and results are as follows:1) A reasonable method of choosing speed ratio and degree of reaction for the small radial turbines was described. A one-dimensional aero-thermal preliminary design code OCC was programmed by analyzing all kinds of restriction factors on the speed ratio and degree of reaction. The design results for a600kW radial turbine nozzle and rotor blade by using the code OCC were compared with the results by the code OFC in the literature. The main parameters between the two designs were in agreement and the total to total isentropic efficiency of the radial turbine designed by the OCC is larger than that by the OFC. The three-dimensional flow calculation is conducted for the design by the OCC. The comparisons between the CFD results and the OCC results for the radial turbine showed that the results were in agreement. The present design method and the one-dimensional design code OCC are appropriate to the preliminary design of small radial turbines.2) The design method based on the two-dimensional analysis of the radial turbine inlet volute was discussed and the design code was programmed. The geometric parameters of the volute cross sections can be obtained by using the method and the design code. The3D volute is modeled with UG according to the volute design results.3) The3D flow fields of the whole radial turbine including the inlet volute, all the passages of nozzle and rotor blade are calculated. The flow inside the turbine and the overall performances were analyzed. The results indicate that the design of the stator is rather successful and the impeller still needs to be improved.4) An aerodynamic optimization platform for radial turbines is developed, which consists of the modules of geometry parameterization by means of NURBS, CFD flow simulation and advanced optimization algorithm. The optimization of the rotor blade of the600kW radial turbine was carried out and the turbine total to total efficiency increased by0.12%.