Numerical study on unsteady film cooling performance of turbine rotor considering influences of inlet non-uniformities and upstream coolant

Abstract

High-pressure turbine (HPT) rotor blades work in a harsh environment with high temperature and rotational speed. Affected by blade row interaction and inlet non-uniformities, the rotor flow field behaves with significant unsteady characteristics. In order to study the unsteady film cooling performance of the rotor blade, unsteady numerical simulations were conducted on the film-cooled first stage vane and blade of GE-E3 engine HPT. Time-resolved results of cases with hot streak (HS) and combined HS and swirl were compared to the case with uniform inlet total temperature and velocity to investigate the effect of inlet non-uniformities. A simulation with non-film-cooled stator vane (NFCS) was also studied to reveal the impact of stator film coolant. The results showed that unsteady film cooling effectiveness fluctuations at the leading edge (LE) region are the most significant, with the mean-to-peak fluctuation amplitude reaching over ±100%. LE cooling air unsteady excursion induced by the stagnation line oscillation is the main cause of this behavior. Vane coolant and inlet non-uniformities have shown a distinguished influence on the coolant attachment and migration at LE, thus affecting the film cooling effectiveness. At blade pressure side (PS) and suction side (SS), vane coolant and inlet non-uniformities affect the fluctuation amplitude of film cooling effectiveness by changing the static pressure perturbation behavior. Simultaneously, the existence of HS will decrease the SS time-averaged film effectiveness by a factor of 10%. In comparison, swirl has shown a negative effect on PS film effectiveness by a factor of 6%.