基于多孔介质的指尖密封各向异性传热模型

Anisotropic heat transfer model of finger seal based on porous media

在指尖密封多孔介质流动模型的基础上,将指尖密封片之间的接触传热附加于固体导热之中,之后通过对密封固体结构与结构内流体的耦合各向异性传热进行理论分析,建立了指尖密封各向异性传热数学模型;基于商业软件Fluent中的用户自定义标量(UDS)方程功能,开发了多孔介质各向异性传热数值计算模块,并数值模拟了指尖密封结构内的流动与传热特性。结果表明:指梁与指尖靴区域的各向异性有效导热系数张量与孔隙率、径向和周向位置以及轴向接触热阻等因素相关;指尖密封最高温度出现在指尖靴与转子接触面的略下游处;与各向同性传热模型相比,采用各向异性传热模型时,指梁下部和指尖靴区域沿径向和轴向存在较大温度梯度,但温度沿周向的变化两者均很小;泄漏量随着压差的增加逐渐增大,随着转子转速的增加基本不变;指尖密封最高温度值随着压差的增加逐渐减小,随着转子转速的增加逐渐增大。

An anisotropic heat transfer model was built by theoretically analyzing the contact and anisotropic heat transfer characteristics coupled finger seal and fluid flow within the structure on the basis of porous model.Then,an anisotropic heat transfer numerical calculation model was developed on the basis of user-defined scalar（UDS）function of commercial software Fluent,and the heat transfer and flow characteristics of finger seal were simulated.Results showed that the effective thermal conductivity tenser of finger beam and finger foot was related to the factors of porosity,radial and circumferential position,and axial contact resistance.The highest temperature of finger seal appeared slightly downstream the contact surface between finger foot and rotor.Besides,compared with isotropic heat transfer model,the temperature decreased greatly at radial and axial directions in finger foot and lower part of finger beam zones while using anisotropic heat transfer model,however,it remained unchanged in circumference both of them.Seal leakage increased with the increasing pressure differential but kept stable with the increasing rotation speed.The height temperature decreased with the increasing pressure differential but increased with the increasing rotation speed.