Rf. Martinezbotas et al., HEAT-TRANSFER MEASUREMENTS IN AN ANNULAR CASCADE OF TRANSONIC GAS-TURBINE BLADES USING THE TRANSIENT LIQUID-CRYSTAL TECHNIQUE, Journal of turbomachinery, 117(3), 1995, pp. 425-431
Heat transfer measurements have been made in the Oxford University Col
d Heat Transfer Tunnel employing the transient liquid crystal techniqu
e. Complete contours of the heat transfer coefficient have been obtain
ed on the aerofoil surfaces of a large annular cascade of high-pressur
e nozzle guide vanes (mean blade diameter of 1.11 m and axial chord of
0.0664 m). The measurements are made at engine representative Mach an
d Reynolds numbers (exit Mach number 0.96 and Reynolds number 2.0 X 10
(6)). A novel mechanism is used to isolate five preheated blades in th
e annulus before an unheated flow of air passes over the vanes, creati
ng a step change in heat transfer. The surfaces of interest are coated
with narrow-band thermochromic liquid crystals and the color crystal
change is recorded during the run with a miniature CCD video camera. T
he heat transfer coefficient is obtained by solving the one-dimensiona
l heat transfer equation for all the paints of interest. This paper wi
ll describe the experimental technique and present results of heat tra
nsfer and flow visualization.