截断扰流柱对涡轮叶片前缘冲击冷却的影响研究

Study on the Flow and Heat Transfer Characteristics of Impingement Cooling at the Leading Edge of Gas Turbine with Truncated Pin-fins Array

通过数值模拟研究了错列排布的截断扰流柱高度及布置方式对涡轮叶片前缘双层壁冲击冷却通道的流动和换热特性的影响。通过对通道内不同截面二维流线以及涡核图分析增强了对弯曲双层壁冷却通道内的流动特征的理解,并进一步结合近靶面极限流线和流动特征图印证该流动特征以及壁面流动,基于此,分析了靶面局部换热特性,并讨论了不同方案下的靶面平均努塞尔数、流阻损失和综合换热性能。数值模拟结果表明,截断扰流柱方案较常规全尺寸扰流柱在换热性能上有明显提升且其流阻有一定降低。当截断扰流柱布置在于冲击孔壁面,截断扰流柱相对高度为0.75时,整个靶面的平均换热和综合换热性能最高。基于本文研究结果,在燃气轮机涡轮叶片前缘双层壁通道中,推荐在冲击孔壁上布置一定高度的截断扰流柱,有助于综合换热性能的提升。

Numerical simulations have been carried out to study the influences of truncated pin-fin height and arrangement on heat transfer increment and flow behavior with an array of impingement jets on a concave double wall channel.Two-dimensional sections of streamlines and vortices core pictures in the channel are applied to better understand the flow structures in this model.Flow topology figure conjugated with limiting streamlines near the target surface are added to illustrate the flow near the target.The local heat transfer characteristics are analyzed based on the flow analysis results.The overall parameters,i.e.,averaged Nusselt number,friction factor,thermal performance,are also obtained.The numerical results show that the introduction truncated pin-fins shows a better heat transfer performance with lower pressure drop than the whole pin-fin case.And the case of truncated pin-fins placed on the jet-hole surface with a relative height of 0.75 reaches the highest averaged Nusselt number and overall thermal performance.It is recommended to add truncated pin fins placed on the jet-hole surface in the double wall jet impingement channel for gas turbines blade leading edge.