旋转对冲击射流流动及换热影响的数值研究

Numerical investigation on effect of rotation on flow and heat transfer of impinging jets

为了探究旋转对动叶前缘冲击射流流动及换热的影响机制,采用数值模拟的方法对比分析了静止条件和三种不同旋转转速下的流场结构与换热情况。结果表明:冲击靶面的平均努塞尔数随转速的增大而减小,最高转速下,靶面平均努塞尔数下降约16%。另一方面,压力面和吸力面侧对旋转的敏感性不同。高转速下,换热的削弱主要集中在吸力面和压力面无量纲弧长s/d小于2的区域,压力面s/d大于2区域的换热略有增强;旋转对流场结构产生了明显的影响,旋转改变了射流孔的流量分配,在科氏力的作用下,射流向压力面偏转,这种特征随转速的增大而更加显著。另外,旋转通道内的离心力改变了局部横向流强度。

In order to explore the effects of rotation on impinging jets flow and heat transfer characteristics of the blade leading edge, the flow structure and heat transfer distribution were studied by numerical method. Furthermore, the differences between the stationary condition and three rotation speeds were compared and analyzed. Results showed that the target average Nusselt number decreased with the increase of the rotation speed. At the highest rotation speed, the target average Nusselt number was reduced by 16%. On the other hand, the sensitivity of pressure side and suction side to rotation was different. At high rotation speed, the decrement of heat transfer was mainly concentrated on the entire suction side and the area where the dimensionless curve length s/d was less than 2 on the pressure side, while the heat transfer in the area where s/d was greater than 2 on the pressure side was slightly enhanced. Rotation had a significant effect on the flow structure. The mass flow distribution of the jet holes was changed by rotation, and Coriolis forces deflected jets to the pressure side. This feature became more pronounced with the increase of rotating speed. In addition, the centrifugal force in the rotating channel changed the local intensity of crossflow.