Computational study of a midpassage gap and upstream slot on vane endwall film-cooling

Turbines are designed to operate with high inlet temperatures to improve engine performance. To reduce NO_x resulting from combustion, designs for combustors attempt to achieve flat pattern factors that results in high levels of heat transfer to the endwall of the first stage vane. Film-cooling is still one of the most effective cooling methods for many component features including the endwall. This paper presents results from a computational study of a film-cooled endwall. The endwall design considers both an upstream slot, representing the combustor-turbine junction, and a midpassage slot, representing the mating between the adjacent vanes. The focus of this study is on comparing adiabatic effectiveness levels on the endwall with varying leakage flowrates and gap widths. Results indicate reasonable agreement between computational predictions and experimental measurements of adiabatic effectiveness levels along the endwall. The results of this study show that the midpassage slot has a large influence on the coolant coverage. It was also shown that by raising the combustor relative to the downstream vane endwall, better coolant coverage from the combustor-turbine slot could be achieved.