Measurements with a heat flux microsensor deposited on a transonic turbine blade

Heat flux measurements are reported using a sensor directly deposited on the surface of aluminum gas turbine blade models. The H eat Flux Microsensor consists of a thin thermal resistance layer sandwiched between many temperature sensors forming a thermopile. It is made with microfabrication techniques and is so thin (2 μm) that it is difficult to measure its presence. The sensor is capable of sampling frequencies of at least 100 kHz and allows measurement of a heat flux turbulence intensity analogous to that for velocity. The measurements were carried out in a transonic cascade tunnel. The facility is designed to match dimensionless heat transfer, temperature ratio, flow, and shock structure of gas turbine engines. Results are presented for ten runs at exit Mach numbers of 1.12, 1.16, 1.22, and 1.26. Two of the runs used no internal cooling and were taken to establish a relationship for the adiabatic wall temperature, T_aw . The average heat transfer coefficients at the various Mach numbers were found to match well with predictions from computer models