Aerodynamic Performance Research On Transonic Hige Pressure Stage Of Air-Cooled Turbine

In order to obtain higher thrust weight ratio, nowadays, aero engine improves inlet temperature of turbine and reduces turbine stage constantly. High temperature and high expansion ratio lead to local transonic in the turbine. The advanced air-cooled turbine aerodynamic design idea is to realize blade surface's maximum cooling effect, base on there is not effect on performance ability of turbine. It makes the research of cooling air and main stream mixing become to a key problem in the turbine design. In this paper, the effect of trailing cool-air injection on flow field, the blade profile design which consider the cool-air injection effects and effect of unsteady local optimize design on flow field have been analyzed and studied in detail.At first, numerical simulations have been carried out on stator trailing cool-air injection in different schemes, the effects of different cool-air injection methods and different cool-air injection mass on the intensity of stator trailing shock wave and downstream rotor flow field have been analyzed. Result shows that, slot cooling on suction side of trailing edge can reduce the intensity of trailing shock wave and mixing loss, improve flow field. Slot cooling on trailing point can reduce the intensity of trailing vortex and trailing loss, but its mixing loss is bigger. Rotor's inlet flow angle reduces with the mass increasing of cool-air injection. Effects of cool-air injection on the mach number of rotor blade shroud part is weaker than other parts.Secondly, the feasibility of a transonic air cooled turbine blade profile with depression feature at leading edge and injection cool-air at shock wave reflection point to reduce the intensity of shock wave has been researched. Results shows that, new blade profile can control the cool-air vortex in the depression part. Compared with traditional blade, new blade profile's main flow is more reasonable. Injecting cool-air at shock wave reflection point is a feasibility method to reduce shock wave intensity. When cool-air has been injected near the shock wave reflection point, the cool-air injection has positive role on the reducing of shock wave intensity.Then, the flowing law of transonic high pressure turbine stage with stator trailing edge cooling has been studied in detail. The effects of stator trailing edge wave on the boundary layer separation and rotor's flow field have been analyzed. Theory basis and knowledge reserve have been provided for the study of effects of cool-air and main flow mixing on flow. in high pressure turbine stage.Experimental study could not simulate the real working condition of aero engine entirely, so using the advantage of numerical simulation to study the real working condition of turbine blade has important project meaning. In this paper, in order to study the real working condition of flow field in high pressure turbine stage further, unsteady numerical simulations and system analyses have been carried out on different schemes of high pressure turbine stage with cool-air injection and without cooling. Results shows that, the effects of unsteady potential flow on stator is mainly in the range between suction side pressure expansion part and trailing edge part; the unsteady fluctuation on rotor's surface is very obviously. Rotor's loading change greatly. The intensity of shock wave at stator trailing edge become in periodicity. Relatively, the pressure side branch of trailing shock wave has been affected smaller by downstream rotor periodicity movement. There is small effect of rotor and stator's unsteady interfere on suction side vortex of trailing edge vortexes, but the effect on pressure side trailing vortex is bigger and its vortex intensity changes acutely. The transfer direction of wake changes with the potential flow of downstream changing. After using positive bowed stator, the unsteady fluctuation of rotor's mid-section has been increased, the fluctuations of rotor's hub-section and shroud-section are smaller than using straight stator. When slot cooling on trailing edge of pressure side has been used, trailing vortexes' pressure side branch has been influenced greater by unsteady effect and the wake's spread direction changes periodically with the effects of rotor's potential flow. When slot cooling on trailing point has been adopted, the potential flow of downstream rotor has very small effect on trailing vortexes and spread direction of wake. Cooling of stator trailing edge makes the rotor's load reduce before 30% chord length and increase behind 30% chord length.