复合翅片传热与流动特性的数值模拟

Numerical simulation of heat transfer and flow characteristics of composite fin

结合纵向涡发生器和开缝的优点,提出一种复合强化传热翅片,并对该种翅片的传热与流动特性进行数值计算。由于翅片结构比较复杂,在三角形小翼及X形开缝区域应用阶梯逼近进行网格划分。复合翅片的强化作用在于两方面:一是在三角形小翼和X形开缝后的流场均产生了纵向涡,对流体产生较强的扰动;二是带状开缝的间断表面抑制了边界层的增长,平均传热系数较高。计算结果表明:复合翅片的传热系数比平翅片高76%～90%、比三角翼翅片高49%～82%、比条缝翅片高6%～36%;复合翅片的综合传热性能系数(j/f1/3)均高于其他三种翅片,是一种强化传热翅片。应用场协同理论和火积耗散方法分析发现,复合翅片改善了温度场与速度场的协同性;其等效热阻小,传热的不可逆程度低。

The composite fin was proposed for the enhance heat transfer, based on the advantages of longitudinal vortex generator and slit. The performance of heat transfer and fluid flow was investigated by numerical simulation. Stepwise approximation method was applied on the mesh generation for the irregular domains of delta winglets computational results show that some recalculating and slit fins due to complex structure of fin. The eddies develops behind the X-shaped slit and triangle winglet, which lead to the disturbances of fluid flow and enhancement of heat transfer. Besides, the interrupted surfaces of strip-slits make the boundary layer thinner, so the high average heat transfer performance can be achieved. Compared with plain fin, fin with delta winglet and slit fin, the performance of heat transfer of composite fin can improve 76%-90%, 49-82%, 6%- 36%, respectively. The overall performance of composite fin is better than other three fins. By applying on the field synergy principle and entransy dissipation principle to analyze the composite fin, the results show that composite fin can improve the synergy of temperature gradient and velocity fields, and its equivalent thermal resistance is smaller and its irreversibility of heat transfer is lower.