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

Increasing combustor fuel-air ratios are a recent area of concern in gas turbine film cooling due to the potential for heat release on the surface of film-cooled components. This investigation compared four different cooling designs on their heat release potential: namely fanned, normal and radial trenched, and ramped. Measurements of heat flux to the downstream surface, when subjected to a reacting mainstream flow, provide a qualitative comparison between the four tested configurations. Furthermore, this work studied the effect of multiple injection points in series along the surface of a flat plate. An upstream set of normal holes and an upstream slot are evaluated on their 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 adiabatic wall temperature calculations. Downstream heat release is suspected to be a result of coolant interaction with local free radical concentrations. Concentrations, volume flow rates and jet to mainstream momentum ratio dictate local equivalence ratio and hence, the available local enthalpy generatio