截面形状对旋转扰流柱通道流动换热特性的影响

Effect of Cross Sections Shape on the Flow Structure and Heat Transfer in a Pin Finned Rotating Channel

为合理设计航空发动机涡轮动叶尾缘冷却结构,采用ANSYS FLUENT软件模拟了四种扰流柱截面形状在旋转状态下的流动换热特性。对比分析了不同旋转数(Ro)和不同扰流柱截面形状时通道内部的三维流场分布、湍流动能分布、努塞尔数(Nu)分布以及阻力系数。其中扰流柱的截面形状包含圆形、菱形、矩形和椭圆形,Ro数包含0、0.2、0.4和0.6四种数值。模拟过程中通道入口雷诺数为7000,壁面恒定热流为1000 W/m^(2)。结果表明,截面形状和旋转数对流动和换热状态有着显著影响,矩形扰流柱通道的换热系数和阻力系数最高;随着旋转数的增加,迎风面和背风面的换热系数差异逐渐增大;在旋转作用下,扰流柱尾缘区域出现了纵向二次流,该二次流显著破坏了壁面附近的边界层,有利于背风面换热增强。

To reasonably design the trailing edge cooling structure of aeroengine turbine blade,the flow structure and heat transfer characteristics of four kinds of cross sections shape under rotating state were simulated by ANSYS FLUENT software.The three-dimensional flow field distribution,turbulent kinetic energy distribution,Nusselt number(Nu)distribution and drag coefficient in the channel with different rotation numbers(Ro)and different cross sections shapes of pin fin are analyzed.The cross sections shapes of the pin fin include circle,diamond,rectangle and ellipse.Ro number includes four values,i.e.,0,0.2,0.4 and 0.6.During the simulation,the Reynolds number for the inlet channel is 7000 and the constant heat flux on the wall is 1000 W/m^(2).The results show that the cross section shape and Ro have significant effects on the flow and heat transfer characteristics,and the highest heat transfer coefficient and resistance coefficient of channel is found at the rectangle pin fin duct;With the increase of rotation number,the difference of heat transfer coefficient between windward surface and leeward surface is increased gradually;Under the action of rotation,the longitudinal secondary flow appears in the trailing part of the pin fin,which significantly destroys the boundary layer near the endwall and is conducive to the heat transfer enhancement.