NUMERICAL STUDY ON THE INFLUENCE OF PURGE SLOT SHAPES ON THE FILM COOLING PERFOMANCE OF ENDWALL WITH THE MAINSTREAM SWIRL

For modern gas turbine design, a slot exists between the first-stage nozzle guide vane and the combustion chamber flame tube due to assembly requirements. This structure's cooling performance is often overlooked or oversimplified in design. However, this article will consider the real combustion chamber exit flow field and conduct a detailed study of the cooling effect under aggressive swirl flow in the slot. This study employs a boundary condition generation method to evaluate the influence of swirling flow under various inlet conditions through numerical methods. The fundamental model consists of a single-row 45-degree slot combination with C3X nozzle guide vane. On this basis, a novel laterally expanding slot is designed. To assess the influence of swirling flow, two cases under two swirling flow orientations were studied. The numerical findings indicate that, under the conventional slot structure, the positive inlet condition can diminish the cooling effectiveness of the purge slot, whereas the negative swirl flow enhances it. Under uniform inlet, the newly designed laterally expanding slot demonstrates an average adiabatic cooling effectiveness surpassing that of the conventional slot, reaching as high as 76%. This innovative design exhibits superior cooling performance under both positive and negative swirl flow inlet conditions, while also maintaining a high degree of robustness in the presence of swirl flows.