Tip leakage flow, heat transfer and blade lifting in a jet engine turbine
An existing Navier-Stokes code (MEFP) was used to calculate developing flow and heat transfer in turbine tip gaps. Successful calculations of the heat transfer to a model turbine blade tip were obtained with a Prandtl mixing length turbulence model. The calculations revealed details of the flow development including recirculation and reattachment on the blade tip surface. The calculated heat transfer distributions were in good agreement with experimental data. A combined solution of the energy equation in the tip gap flow and in the rotor blade tip gave tip temperature distributions.
An independent computational study, using the same numerics as MEFP but a separate new computer program, was also performed to investigate the numerical accuracy of heat transfer calculations for fully developed flow.
A literature survey of gas turbine blade materials and factors influencing turbine tip blade life was performed. Approximate temperature ranges for the significant blade life reduction mechanisms, hot corrosion, oxidation, and melting were determined. calculations for typical jet engine conditions, In the present a maximum tip temperature of 1488 K was predicted which would lead to high oxidation rates for present day turbine blade alloys.