Glossary
What are transonic airfoils, and what is the active clearance control? Check out our technical dictionary and find out more about engine technology terms – from active clearance control to velocity triangle.
Cooling air holes
During engine operation the blades and vanes of the high-pressure turbine which is located just downstream of the combustion chamber are exposed to very high temperatures. Under extreme conditions the gas temperature may even exceed the melting point of the blade or vane material. Therefore, the airfoils of HPT blades and vanes are provided with cooling air holes whose number varies depending on the function and position of the part (blade or vane, stage 1 or stage 2) and may be as high as 400 per airfoil. The cooling medium used is pre-compressed air from the compressor which is forced through the cooling air holes. The holes are produced by laser drilling, electrochemical fine drilling (ECF) or electro-discharge machining (EDM).
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