INFLUENCE OF SHOCK SYSTEMS ON SUCTION SURFACE FILM COOLING IN TURBINE CONVERGENT-DIVERGENT-NOZZLE ROTOR AT OFF-DESIGN CONDITION

Detailed numerical simulations have been carried out to investigate the influence of the fishtail shock and its echo wave on the suction surface film cooling in a vaneless counter rotating turbine convergent-divergent-nozzle rotor at different rotating speeds and blowing ratios.At about 30%axial chord length,a row of cooling holes is evenly distributed along the span.The secondary flow and static temperature on the high pressure rotor suction surface are analyzed at three different rotating speeds of the high pressure turbine stage(5460 r/min,6970 r/min and 7800 r/min respectively) and two different cooling flow velocities(10 m/s and 20 m/s respectively).From the results we can found that,on the suction surface,the static temperature will rise over the location of the shock systems impinging against,and under the different condition,the magnitude of the temperature rise is different.On the both ends of the high pressure rotor suction surface near the trailing edge,the cooling effectiveness declines,especially on the top end,which is mainly led to by the secondary flow there.