基于磁共振测速的复合冷却涡轮叶片流动分析

Flow measurement and analysis of a turbine blade with multiple cooling structures based on magnetic resonance velocimetry

针对传统光学测量技术难以完整地测量涡轮叶片复杂冷却结构内部三维流场的问题,采用磁共振测速(MRV)技术测量了一种复合冷却涡轮叶片内部的三维流场,并重点研究了叶片尾缘的流动特征。在通过MRV数据验证计算流体力学(CFD)准确性和可靠性的基础上,进一步通过CFD研究了全高、半高扰流柱对尾缘弦向出流的影响。结果表明,MRV成功地捕捉到了复合冷却涡轮叶片内部流动特征(如扰流柱和半劈缝处的漩涡结构等)。CFD与MRV数据在尾缘处有一致的出流趋势:气膜孔出流量沿展向逐渐减小,而半劈缝出流量沿展向逐渐增大。通过不同扰流柱设计的尾缘CFD对比发现,全高、半高扰流柱对尾缘流动的影响主要在于增大了流阻和出流的驱动压差,进而改变了出流情况,使得气膜孔整体出流量增大约2.8%,半劈缝整体出流量减小约2.8%。

It is difficult to use the traditional optical measurement technology measure the three-dimensional flow field inside the turbine blade with complex cooling structures.In this paper,the Magnetic Resonance Velocimetry(MRV)technology was employed to investigate the flow behavior inside a turbine blade with multiple cooling structures,par-ticularly the flow in the blade trailing edge.MRV data were then compared with numerical simulations for validation pur-poses,and the effect of full-height or half-height pin fins on the flow out of trailing edge holes/slots was studied numeri-cally.The results show that MRV is able to capture the internal flow characteristics of the cooled turbine blade,such as the vortices around the pin-fins and the slots.Furthermore,both MRV data and numerical results show that along the spanwise direction,the mass flow rate of the film hole decreases,while that of the slot increases.It is also found that the influence of full-height and half-height pin fins on the flow out of trailing edge holes/slots is mainly in increasing the flow resistance and the driving pressure difference of the outflow,thereby changing the mass flow rate through the holes/slots.The full-height and half-height pin fins increase the overall outflow of the film holes by about 2.8%,while reducing that of the slots by about 2.8%.