Effect Of Internal Coolant Crossflow On Film Cooling Effectiveness And Heat Transfer

At present, the cooling actions for the aero-engine turbine blade are usually divide into theinternal cooling and the external cooling. The internal cooling includes jet impingement cooling,ribbed and pin-fin cooling channel, and so on. The external cooling includes film cooling and thethermal barrier coating. So that the film cooling is one of the most important cooling theologies as weknow. However, In the past，a lot of researches used a stagnant plenum to feed the holes，which wasnot necessarily a right means to re-present real engine condition. In fact, the coolant crossflowfeeding the holes is oriented perpendicular to the hot gas flow direction.For this reason, this paper investigates the film holes including the cylindrical hole and thefan-shaped hole. It is performed to evaluate the effect of perpendicular coolant supply direction onfilm-cooling effectiveness, heat transfer and discharge coefficient over a wide range of crossflowratios (Cr=0.5~3.0) and blowing ratios (Br=0.5~2.0). The results of the present investigation showthat: the perpendicular coolant supply forms vortex flow inside film hole, making the interactionbetween coolant jet and primary flow more complicated. For the cylindrical hole, at lower blowingratio, there is little impact on the lateral averaged film cooling effectiveness as compared to theplenum case when the cross flow exist. At higher blowing ratio, the coolant crossflow feeding theholes is benefit to improving film cooling effectiveness, especially when cross flow ratio equals to2；At lower blowing ratio, there is little impact on the heat transfer coefficient ratio of different crossflow ratio. At higher blowing ratio, when the cross flow ratio is low, heat transfer coefficient ratio isnot affected obviously. But, when the crossflow ratio is high, heat transfer coefficient ratio isenhanced in comparison to the plenum feeding case, and the heat transfer coefficient ratio increasesas the cross flow ratio goes up. Under the same blowing ratio, the discharge coefficient decrease asthe crossflow ratio increases. For the perpendicular coolant supply case, the discharge coefficientdecreases in comparison to the plenum feeding case. For the fan-shaped hole, when the blowing ratiois fixed, the perpendicular coolant supply makes the film cooling effectiveness along the centerlinedecrease. At lower blowing ratio, the heat transfer coefficient ratio is almost the same for the differentcrossflow ratio. At higher blowing ratio, the heat transfer coefficient ratio is enhanced in comparisonto the plenum feeding case. The effect of blowing ratio and crossflow ratio on the dischargecoefficient is similar to the cylindrical hole.