Investigations on the interaction between the front and aft purge flow and the downstream vane of 1.5-stage turbine

Abstract The present work reports the influence of the 1.5-stage turbine flow field by the front and aft rim seal flow. The interaction between the front and aft purge flow and the mainstream of a 1.5-stage turbine was numerically simulated, and the influence of the front and aft purge flow on the downstream vane was analyzed separately. The results show that the front purge flow is distributed at the higher radius of second vane inlet, which changes the position of the blade hub secondary flows, and the aft purge flow is distributed at the low radius. The purge flow at different locations in the aft cavity exit forms shear induced vortex, pressure and suction side legs of the egress, which converges with the suction and pressure side legs of the horse vortex to form vane hub passage vortex. The increased purge flow rate in both the front and aft cavities significantly increases the sealing effectiveness of the rim seal, but also causes a reduction in turbine efficiency. The combined effect of the front and aft purge flow reduces the turbine efficiency of the end-wall structure by 0.3619, 0.9062, 1.5004, 2.0188 and 2.509% at IR = 0, IR = 0.5%, IR = 0.9%, IR = 1.3% and IR = 1.7%.