Turbine blade platform film cooling with simulated stator-rotor purge flow with varied seal width and upstream wake with vortex

摘要

The turbine blade platform can be protected from hot mainstream gases by injectingcooler air through the gap between stator and rotor. The effectiveness of this filmcooling method depends on the geometry of the slot, the quantity of injected air, and thesecondary flows near the platform. The purpose of this study was to measure the effectof the upstream vane or stator on this type of platform cooling, as well as the effect ofchanges in the width of the gap.Film cooling effectiveness distributions were obtained on a turbine blade platform withina linear cascade with upstream slot injection. The width of the slot was varied as well asthe mass flow rate of the injected coolant. Obstacles were placed upstream to model theeffect of the upstream vane. The coolant was injected through an advanced labyrinthseal to simulate purge flow through a stator-rotor seal. The width of the opening of thisseal was varied to simulate the effect of misalignment. Stationary rods were placedupstream of the cascade in four phase locations to model the unsteady wake formed atthe trailing edge of the upstream vane. Delta wings were also placed in four positions tocreate a vortex similar to the passage vortex at the exit of the vane. The film coolingeffectiveness distributions were measured using pressure-sensitive paint (PSP).Reducing the width of the slot was found to decrease the area of coolant coverage,although the film cooling effectiveness close to the slot was slightly increased. Theunsteady wake was found to have a trivial effect on platform cooling, while the passagevortex from the upstream vane may significantly reduce the film cooling effectiveness.