Coupling evolution and interaction mechanism of multiple leading-edge coolant vortices and boundary layer in turbine cascade

Persistent efforts in thermal design have been made to enhance the cooling effectiveness of film cooling through the control of CRVP (counter-rotating vortex pair). Coolants bring inevitable aerodynamic loss to turbine stage. Due to the complex mixing process in turbine stage, turbine designers tend to treat the coolants as jets with momentum injections, ignoring the inherent evolution and interaction mechanism of coolant vortices. To reveal the relationship between the vortex evolution characteristic and loss mechanism, our research has thoroughly analyzed the evolution mechanism of multiple CRVPs and the interaction with boundary layer and wake. Furthermore, both qualitative and quantitative loss analysis are conducted on boundary layer to reveal the dominant source of mixing loss. The results indicates an adversarial relationship between upstream and downstream CRVP, leading to intense influence on the evolution of boundary layer and wake, which dominates the loss evolution characteristics on pressure side and suction side. Hole geometric parameters notably affect the vortex evolution process, resulting in various aerodynamic and cooling performance. Choice of hole geometric parameters is discussed in this paper to obtain balanced aerodynamic and cooling performance, which provides a certain support for aero-thermal coupling design in cooling turbine.