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

Currently, turbines are being designed to operate with increasing inlet temperatures to improve the engine's performance. To reduce NO_x combustion, combustors are being designed to provide flat pattern factors. For these reasons, the endwall of the first stage vane is under severe heat transfer conditions. Film-cooling is one of the most effective cooling methods for the endwall of the vane. This paper presents results from a computational study of a film-cooled endwall. The endwall design considers both an upstream slot and a mid-passage slot, whereby the slot considered is both aligned and misaligned with respect to the endwall. Results indicate reasonable agreement between computational predictions and experimental measurements of adiabatic effectiveness levels along the vane endwall. The results of this study show the mid-passage slot has a large effect on the endwall film coverage. In addition, the relative height of the upstream slot to the downstream endwall is important to consider for improving the cooling benefit from the leakage flow between the combustor and turbine.