Numerical Simulation Of High-Expansion Ratio Transonic Turbine Cascade

With the development of modern aircraft engines and gas turbines, the increase in thrust-to-weight ratio and specific power leading to the requirements of turbine load are also increasing. Therefore, the technology that can effectively improve the load in high load transonic turbine has become an important direction of the turbine development. Different from the conventional turbine, the flow field organization in high expansion ratio transonic turbine may be more complicated. In the supersonic flow region, flow parameters are changed dramatically and shock waves are generated.The interaction between shock waves and boundary layers in the cascade passage makes the boundary layer separated, entropy increased sharply, loss in the cascade increased. Especially in the condition of off-design conditions, the flow characteristics in high expansion ratio transonic turbine are greatly different from subsonic turbine. Therefore, further study of the performance of high expansion ratio transonic turbine at design and off-design condition becomes extremely important.In order to analyse the flow characteristics in high expansion ratio transonic turbine, this thesis studies the flow properties by both experimental and numerical simulation.Firstly, this paper studies high expansion ratio transonic turbine cascade in the condition of low mach number by experiment. Studies in the condition of five angles of inlet:0°、±10°、±20°and three pressure ratios1.9、2.1、2.3. Through the analysis of the experimental results, some of the flow phenomena in the flow process of high expansion ratio transonic turbine can be understood. Using Fluent and NUMECA simulate the cascade, angles of inlet are the same as in the test, pressure ratios are1.9、2.1、2.3、3、3.5、4、4.5. Compares the numerical results with the tests in the same condition, NUMECA results is more close to the real flow. Secondly, analyzes the Numeca results from loss of energy、distribution of static pressure coefficient、changes of the internal flow structure, etc, understands the characteristics of the flow in the turbine,explains the flow phenomena and the effeets of pressure ratio and angle of inlet to the performance of high expansion ratio transonic turbine...