旋转对弯扭涡轮叶片前缘气膜冷却的影响

Effect of rotation on the leading-edge region film cooling of a twisted turbine blade

基于热色液晶(TLC)测温技术,开展了转速(攻角)和吹风比对弯扭涡轮叶片前缘区域气膜冷却效率分布影响的实验研究。实验中涡轮转速分别为400r/min(正攻角)、550r/min(零攻角)和700r/min(负攻角),平均吹风比为0.5~1.25。冷却工质采用氮气,对应的射流-主流密度比为1.04。基于涡轮动叶弦长的涡轮出口主流雷诺数为60 800。实验结果表明:转速是决定涡轮叶片前缘气膜冷却效率分布最重要的参数之一。随着转速的增大,滞止线的位置会从压力侧(PS)移动到吸力侧(SS)。当吹风比相同时,面平均气膜冷却效率随转速的增大而逐渐增大;当转速相同时,面平均气膜冷却效率随吹风比的增大而增大。

An experimental investigation was performed to investigate the effects of the rotation and blowing ratio on the film cooling effectiveness distributions of the leading-edge regions of a twist gas turbine blade using a thermochromic liquid crystal(TLC)technique.The experiments were carried out at three rotating speeds,including 400 r/min(positive incidence angle),550 r/min(zero incidence angle),and 700 r/min(negative incidence angle).The averaged blowing ratio varied from 0.5 to 1.25.Nitrogen was used as the coolant to ensure that the coolant-to-mainstream density ratio kept at 1.04.The Reynolds number,based on the mainstream velocity of the turbine outlet and the rotor blade chord length,was 60 800.The results show that rotating speed is one of the most critical parameters in determining the film cooling effectiveness distributions on the leading edge.The position of the stagnation line moved from the pressure side(PS)to the suction side(SS)with the increase in rotating speed.Under the same blowing ratio,the area-averaged film cooling effectiveness increases monotonously with the increase in rotating speed.Under the same rotating speed,the area-averaged film cooling effectiveness increases with the increase in blowing ratio.