Experimental And Numerical Investigation On Turbine Cascade Loss

The internal flow in turbines is three-dimensional and viscous, and aerodynamic performance of turbine cascade can be significantly affected by turbine blade profile loss and secondary flow loss. Therefore In order to improve the aerodynamic performance of turbine, it is necessary to study the influence factors of turbine aerodynamic performance.Firstly, in order to study the effect of inlet incidence angle and outlet Mach number on profile loss, turbine test rig of straight cascade turbine test rig is built. Aerodynamic performance experiment of straight cascade is carried out, in which inlet incidence angle and outlet Mach number are changed. Pressure distribution at outlet is tested in this experiment,and so does that on the blade surface. The Mach number influence (0.5, 0.6 and 0.7) on straight cascade aerodynamic performance is studied when inlet incidence angle is 0°. Inlet incidence angle (-10°, 0°and 10°)is changed in this experiment,and its influence on turbine flow fields is studied at the Mach number of 0.6. The results indicate that blade load and total pressure loss increase along with the increase of inlet incidence angle. The blade load and total pressure loss at outlet grow with the increase of Mach number.Then, in order to study the effect of cooling-air injection at straight cascade trail edge on profile loss, turbine test rig of cooling-air injection at straight cascade trail edge is established. Aerodynamic performance of straight cascade with cooling-air injection at cascade trail edge is examined in this paper. Pressure distribution at outlet is tested in this experiment, and so does that on the blade surface. The Mach number influence (0.7, 0.8 and 0.9) on aerodynamic performance is studied without cooling-air injection at trail edge. By contrast, the experiment with cooling-air injection at trail edge is conducted at different Mach numbers (0.7, 0.8 and 0.9).The results demonstrate that blade load and total pressure loss increase with the increase of Mach number. When the Mach number is 0.8, the cooling-air injection quantity (5%, 10% and 15%) influence on blade load and total pressure loss is conducted. The experiment results show that total pressure loss first rises and then declines along with larger cooling-air injection quantity at trail edge. However blade load changes little.Finally, in order to study the effect of inlet incidence angle and outlet Mach number on turbine endwall loss,turbine test rig of annular sector cascade of high Mach number is performed. Aerodynamic performance experiment of annular sector cascade of high Mach number is carried out, where inlet incidence angle and outlet Mach number are changed in this experiment. Again, pressure distribution at outlet is investigated in this experiment, as well as that on the blade surface at different blade heights (10%, 50% and 90%). The Mach number influence (0.7, 0.8 and 0.9) on annular sector cascade aerodynamic performance is studied when inlet incidence angle is 0°. The results show that blade load and total pressure loss at outlet grow with the increase of Mach number. Inlet incidence angle (-15°, -7.5°, 0°,7.5° and 15°) is changed in this experiment, and its influence on turbine flow fields is studied at the Mach number of 0.8. It can be seen that total pressure loss first increase and then declines along with the increase of inlet incidence angle.