Numerical study on the coupled influence of combustor flame tube cooling holes pre-swirl and mainstream swirl on the film cooling perfomance of endwall

Extensive research has been conducted into the interaction between the combustion chamber and nozzle guide vanes, with a growing emphasis on the influence of upstream chamber coolant on the vane endwall's cooling performance. Studies have suggested that slot structures may potentially weaken endwall cooling effectiveness. This investigation delves into the potential of flame tube coolant to improve turbine endwall cooling design. Utilizing a coupled geometry model based on the C3X model and actual aeroengine dimensions, this study elucidates the mechanisms of endwall cooling performance degradation in the presence of slot structures. Subsequently, the study examines the individual impacts of flame tube cooling hole pre-swirl and mainstream swirl on endwall cooling dynamics. And the interaction between pre-swirl cooling holes and swirl mainstream is also explored. The findings reveal that introducing a 45 degrees pre-swirl to flame tube cooling holes enhances coolant coverage, thereby enhancing the adiabatic cooling effectiveness by 21% and correspondingly diminishing the net heat flux reduction. Both swirl mainstreams reduce the net heat flux reduction, yet selecting negative inlet conditions can yield relatively superior cooling outcomes. The 45 degrees pre-swirl configuration maintains optimal coolant coverage and net heat flux reduction across all inlet conditions. However, optimal adiabatic cooling efficiency is achieved without a 45 degrees pre-swirl design under negative inlet conditions, and the lowest reduction in net heat flux reduction occurs. These findings inform the design of an upper and lower endwall cooling strategy.