Impact of Trench and Ramp Film Cooling Designs to Reduce Heat Release Effects in a Reacting Flow

Abstract

High freestream fuel-air ratios are a recent area of concern in film cooling due to the potential for heat release on the surface of film cooled turbine components. This investigation compared the potential for heat release from three cooling designs: namely a fanned, a trenched, and a ramped. Measurements of heat flux to the downstream surface are provided when subjected to a reacting mainstream flow. This work furthermore studied the effect of multiple injection points in series along the surface of a flat plate. The extremes of either an upstream set of normal holes or an upstream slot is evaluated on its ability to protect the downstream coolant flow from the fuel rich mainstream. Results are presented in terms of heat flux, augmentation of heat flux, and normalized temperature which quantifies the magnitude, change, and potential change of downstream heat release, respectively. Downstream heat release was expected to be a result of local equivalence ratio and characteristic chemical and flow times. Results suggest the method of coolant injection to be more impactful on local equivalence ratio than the volume of coolant injected.