Coupling mechanism of combustor swirl and contraction geometry on asymmetric endwall film cooling

The significant film cooling performance disparity between the upper and lower turbine endwalls, induced by combustor outlet swirl and contraction section effects, presents a notable challenge to conventional design assumptions. To address this, an integrated numerical model coupling a swirl combustor with a turbine endwall was established. It reveals that combustor swirl actively reconstructs the cascade mainstream velocity field, creating asymmetric near-wall flows and altering coolant migration, an influence surpassing the passive effect of asymmetric contraction structures. While symmetric contraction geometries weaken the directional sensitivity of swirl, asymmetric contraction coupled with swirl shows strong directional dependence, where positive swirl amplifies the cooling difference between endwalls and reverse swirl suppresses it. Employing the coolant trajectory slope difference method to decouple the individual contributions of swirl and contraction configuration, this study clarifies their differential regulation mechanism on endwall film cooling and thus provides theoretical support for the integrated optimal design of combustor-turbine cooling systems.