MAINSTREAM TURBULENCE EFFECT ON FILM EFFECTIVENESS AND HEAT-TRANSFER COEFFICIENT OF A GAS-TURBINE BLADE WITH AIR AND CO2 FILM INJECTION

Effect of grid-generated mainstream turbulence on the film effectivene ss and heat transfer coefficient of a turbine blade model was investig ated at a chord Reynolds number of 3 x 10(5). The blade model had thre e rows of film holes in the leading edge region and two rows each on t he pressure and suction surfaces. CO2 and air, with density ratios (DR s) of about 1.5 and 1.0, respectively, were used as film injectants. R esults indicate that an increase in mainstream turbulence causes an in crease in Nusselt numbers and a decrease in film effectiveness, over m ost of the blade surface, for both density ratio injectants at all blo wing ratios.