Cooling effectiveness measurements of film cooling configuration on the suction and pressure surface of nozzle guide vane

摘要

Detailed experiments were carried out to obtain the film cooling effectiveness distribution on the suction and pressure surface of a nozzle guide vane provided with two pairs of film cooling hole rows on each surface. Experiments were carried out varying the blowing ratio in the range of 0.35 to 2.5 and coolant to mainstream density ratio in the range of 0.97 to 1.57. The results indicate that the magnitude of the adiabatic effectiveness was lower and the decay of adiabatic effectiveness faster on the pressure surface in comparison to those on the suction surface indicating the effect of surface radius of curvature. The film cooling effectiveness data obtained on the suction surface indicate that at higher coolant to mainstream density ratio the film effectiveness decays faster and at larger downstream distances the magnitude was lower than that for lower coolant to mainstream density ratio. The results also indicate that on the suction surface in the case of flow through both the two pairs of hole rows the effectiveness distribution downstream of the second pair of row can be estimated with satisfactory accuracy using the correlation for additive effect of film cooling. Film cooling effectiveness data can be used to estimate the adiabatic wall temperature and hence the estimation of blade metal temperatures.