Performance of a tip shroud with film cooling and labyrinth seals

Abstract

The use of the tip shrouds is effective in reducing leakage flow. Film cooling is required to keep the hot gas separated from the shroud surface. This paper investigates the effects of film cooling on the cooling effectiveness and aerodynamic performance of a shrouded turbine cascade by numerical calculations. The flow structures of a single-side labyrinth seal and a double-side labyrinth seal are analyzed in detail, respectively. Compared to the unshrouded cascade, they reduced relative leakage by 27.1% and 49.7%, respectively. The introduction of coolant enhanced the sealing ability. Due to the recirculation zone, the cooling effectiveness at the shroud surface of the single-side labyrinth seal and double-side labyrinth seal is 0.0634 and 0.0481 at the blowing ratio of 0.5, respectively, and 0.0852 and 0.0759 at the blowing ratio of 1. Compared to the conditions without film cooling, the average total pressure loss at the outlet of the shrouded cascade with a single-sided labyrinth seal increased by 3.35% and 1.82% at blowing ratios of 0.5 and 1, respectively. For the shrouded cascade with a double-sided labyrinth seal, the total pressure loss increased by 2.23% and 2.20% at the same blowing ratios.