ENDWALL HEAT-TRANSFER MEASUREMENTS IN AN ANNULAR CASCADE OF NOZZLE GUIDE VANES AT ENGINE REPRESENTATIVE REYNOLDS AND MACH NUMBERS

Aerodynamic and heat transfer measurements have been made on the hub a nd casing endwalls of a large (mean diameter 1.1 m) annular cascade of high-pressure nozzle guide vanes. The measurements have been made ove r a range of engine representative Mach and Reynolds numbers and with large levels of free-stream turbulence intensity. The transient liquid crystal technique has been employed, which has the advantage of yield ing full surface maps of heat transfer coefficient. Aerodynamic measur ements of Mach number distributions on the end-wall surfaces are also presented, along with surface-shear flow visualisation using oil and d ye techniques. The heat transfer results are discussed and interpreted in terms of the secondary flow and Mach number patterns.