预旋角对径流涡轮背盘射流冷却的影响

Influence of Pre-swirl Angle on the Effectiveness of Back-disk Jet Cooling for Radial Turbines

采用背盘射流冷却技术对径流式涡轮机热负荷较大的区域进行冷却。采用气热耦合的方法,研究了该冷却技术在预旋角为60°~120°内对背盘冷却特性的影响。结果表明:背盘射流冷却可以大幅提高径流涡轮背盘的冷却效率;预旋角为60°时背盘冷却效果最好,随着预旋角的增加,背盘冷却效果变差;相同径向位置时,冷却系数在0.01~0.02,预旋角每增加15°,背盘平均冷却效率约降低0.003,当冷却系数为>0.02~0.04时,预旋角每增加15°,背盘平均冷却效率降低0.016~0.050;冷却流体流入涡轮主流流道后,涡轮机效率受到冷却流体的影响而降低,当预旋角为60°时,冷却流体对涡轮机效率影响最小。

Back-disk jet cooling technology is used to cool the region in a radial turbine where the heat load is large.A conjugated heat transfer(CHT)simulation was carried out to study the effects of pre-swirl angle on the back-disk cooling characteristics in the angle range of 60°-120°.Results show that the back-disk jet flow could greatly improve the cooling efficiency for radial turbines.The cooling effectiveness reaches the optimum at the pre-swirl angle of 60°,and then,with the increase of pre-swirl angle,the cooling effectiveness gets worse.At the same radial position,when the cooling coefficient lies in the range of 0.01-0.02,the average cooling efficiency of the back-disk would drop by 0.003for every increase in pre-swirl angle by 15°;and when the cooling coefficient lies in the range of>0.02-0.04,the average cooling efficiency would drop by 0.016-0.050for every increase in pre-swirl angle by 15°.When the cooling fluid flows into the main channel of a radial turbine,the turbine efficiency would be reduced accordingly,and the minimum impact could be reached at the pre-swirl angle of 60°.