圆管内置不同形状涡产生器管内流动特性的数值分析

Numerical Study of the Flow Characteristics in a Circular Tube Fitted with Different Shape Vortex Generator

圆管内置涡产生器是一种被动式的强化传热方式。涡产生器在管内诱导产生的二次流是强化传热的主要原因,而二次流强度受制于流动参数和涡产生器的结构参数。本文采用数值方法对圆管内置不同形状涡产生器的流动特性进行了研究。研究结果表明:不同形状涡产生器在圆管内产生的平均二次流强度和沿流动方向的局部二次流强度依次为等腰梯形涡产生器最强,直角梯形涡产生器次之,矩形涡产生器最弱;在传统扭带基础上裁除材料面积相同的条件下,涡产生器形状对管内流体的平均阻力系数和沿流动方向的局部阻力系数影响甚微。对比不同位置的二次流强度云图发现,与基带处相比,涡产生器在圆管内诱导产生了更强的二次流。内置不同形状的涡产生器后,管内流体的二次流强度分布和流线分布发生变化,与其余三种形状的涡产生器相比,等腰梯形涡产生器诱导产生的二次流更强。

The vortex generator inserted into a circular tube is a passive heat transfer enhancement method. The secondary flow induced by the vortex generator in the tube is the main reason for the heat transfer enhancement, and the intensity of secondary flow is subject to flow parameters and the structural parameters of vortex generators. In this paper, the numerical method is used to study the flow characteristics of the different shapes vortex generators inserted into the circular tube. It is found that the average secondary flow intensity and the local secondary flow intensity along the flow direction generated by the vortex generators with different shapes are the strongest in the order of isosceles trapezoidal vortex generators, followed by right-angle trapezoid vortex generator and the weakest in the rectangular vortex generator. When the geometric area of material cut from the traditional twisted tape to form different vortex generator inserts is identical, the shape of vortex generator has little influence on the average friction factors and the local friction factors along the flow direction. By comparing the secondary flow cloud graphs at different locations, it is found that compared with the baseband, the vortex generator induces stronger secondary flow in the tube. When vortex generators with different shapes are built in, the secondary flow intensity distribution and streamline distribution of the fluid in the tube change. Compared with the other three vortex generators with different shapes, the isosceles trapezoidal vortex generator can induce stronger secondary flow.