Aerodynamic Design And Numerical Investigation Of High Expansion Ratio Two Stage Turbine

Power system is the core component of various aviation, aeropace, and navigation equipment. The performance of power system exerts significant effect on the overall performance of these kinds of equipment. Power systems normally consists of electro-dynamic system and thermal-dynamic system. Electro-dynamic system has small voyage, low speed, and small noise features. Thermal-dynamic system has large output power, energy flux density and nosie feasure. Considering the merits of large power and voyage of thermal-dynamic system, the paper chooses it as power system, and designs a two-stage large pressure ration turbine.The thesis aims to conduct aerodynamic design and numerical simulations of this kind of turbine. To produce enough output power and high efficiency, the designed turbine works under optimum velocity ratio. In the turbine, the stator has to work under high enthalpy drop, so Laval nozzles are used to produce high speed gas. Also, to avoid too small blade height, partial admission scheme is used.In the design process, firstly, one-dimensional aerodynamic design is conducted; basic parameters are calculated. Secondly, three-dimensional modeling and numerical simulations are conducted. The results shows that the mass flow and the output power meet the design requirements. Also, by analyzing numerical results, the performance and flow characteristics in nozzles, the flow separation, shock wave phenomenon in rotor passage, and the effect of partial admission on aerodynamic parameter distribution and load of rotor blades are investigated. Then, finite element analysis is conducted on rotor blade, to analyze the deformation and strain of blades. The results shows that stress concentration area is on blade root. At last, several kinds of diffuser pipe are designed and investigated by numerical method. By using the diffuser pipe which expands gradually, and has rough surface, the diffuser piper can produce low speed gas and elevate uniformity of aerodynamic parameters at outlet under small energy loss.