流道内涡街诱导弹性体振荡强化传热分析

Analysis of Enhanced Heat Transfer for Oscillation of Elastomer induced by Vortex Street in a Flow Channel

以具有固定扰流圆柱的冲孔矩形涡流发生器通道内换热强化为研究对象,采用任意拉格朗日-欧拉(ALE)法模拟了流道内涡街诱导弹性体振荡强化换热现象。通过对比分析流道内的流动损失E、净换热量Q和热效率因子η,研究了弹性体抗弯刚度及安装角度对通道内流体流动和换热的影响。结果表明:流体经刚性圆柱产生涡街,诱导弹性体发生振荡,尾涡在弹性体达到最大形变时从后缘脱落进入下游中,其形成的二次流不断扫掠热边界层,使得壁面附近热流体与来流冷流体相互掺混,从而有效强化换热;抗弯刚度越低,弹性体振荡位移越大,在低流动损失前提下产生的净换热量越高,从而显著提高换热效率;弹性体安装倾角为π/4、抗弯刚度为0.25时净换热量提升最显著,较常规通道提升88.5%,较刚性体通道提升82.7%;热效率因子在采用弹性体的通道内均高于刚性体情况,弹性体安装角度β为π/2时热效率因子最高,且其在弹性体任何抗弯刚度下较常规通道均有提升。

Based on the enhanced heat transfer in the punch rectangular vortex generator channel with fixed spoiler cylinder, the arbitrary Lagrangian-Eulerian(ALE) method was used to simulate the enhanced heat transfer phenomenon of oscillation of elastomer induced by vortex street in the flow channel. By comparing and analyzing the flow loss E, net heat flux Q and thermal efficiency factor η in the flow channel, the effects of elastomer flexural rigidity and mounting angle on the internal flow and heat exchange of the channel were studied. The results show that the vortex street generated by the fluid flowing through the rigid cylinder drives the downstream elastomer to oscillate. The wake vortex will fall off from the trailing edge into the downstream when the elastomer reaches its maximum deformation, and the secondary flow formed by it will continuously sweep the thermal boundary layer so that the hot fluid near the wall and the incoming cold fluid are mixed with each other, thus enhancing the heat transfer effectively.The lower the flexural rigidity is, the larger the oscillation displacement of elastomer is, and the greater the net heat flux generated under the premise of low flow loss is, so as to enhace the heat transfer efficiency obviously. When the installation inclination angle is π/4 and the flexural rigidity is 0.25, the enhancement of net heat flux is the most significant, which can increase by 88.5% compared with the simple channel, and can increase by 82.7% compared with the rigid vortex generator channel. In the case of elastomer thermal efficiency factor higher than rigid one, the thermal efficiency factor is the highest when the installation angle β is π/2, and it can be improved at different flexural rigidities compared with the simple channel.