Sweeping Arrays for Film Cooling, Year 1

Two parallel paths will be pursued toward developing sweeping jets for more efficient film cooling: experimental and theoretical. Increasing turbine inlet temperature leads directly to greater turbine efficiency. Film cooling technology allows modern turbines to operate above the melting point of blade materials but requires up to 30% of the engine core flow from the compressor to be diverted to cooling hot gas path components instead of extracting work or producing thrust. As turbine temperature continues to increase, more efficient methods to keep mechanical components within their capability limits are essential. Active control can both reduce the necessary cooling flows and improve their effectiveness, directly impacting air-breathing engine performance. Fluidic diverters have no moving parts and require only a pressure source to generate a consistent periodic output flow, typically exhibited as a sinusoidal sweeping pattern, which can be easily tailored for a given application. Fluidic devices are scalable and can be produced at feature sizes commensurate with the cooling passages in current turbine blades. They can be fabricated of the same materials used in engine components or even within the component itself. As such, they are the ideal actuator for turbine engine applications. For film cooling, it is envisioned that a compact array of fluidic devices producing a thin, spanwise sweep of cooling air over a vulnerable hot gas path surface would reduce cooling flow needs while simultaneously improving the coverage of a given surface jet, relative to present technology. More »