The temperature of the gases circulating within modern aerospace turbine engines can be as high as 2000℃, which is higher than the melting point of the nickel alloy used in the combustion chambers and turbine blades themselves. An engine may require as many as 100,000 holes smaller than 1 mm in diameter to provide cooling within the blades, nozzle guide vanes, combustion rings, and afterburners. The components are protected against such extreme temperatures through the use of boundary layer cooling. The temperature of this cooling air can be around 1000℃, which is, though hotter than one would expect cooling air to be, able to protect the surface of the component. As the cooling air passes over the surface, it forms a cooling film to protect the surface from the high-temperature combustion gases.
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