纵向涡强化换热特性及机理分析

HEAT TRANSFER ENHANCEMENT IN A CHANNEL WITH LONGITUDINAL VORTEX GENERATORS AND FIELD SYNERGY PRINCIPLE ANALYSIS

本文在Re=190～1125范围内对两种不同形状纵向涡发生器(矩形、三角形)以两种不同方式(渐缩式、渐扩式)布置于平行通道内的流动换热特性进行了三维数值模拟研究,并利用场协同原理对其换热机理进行了分析。结果表明:纵向涡使通道换热得到很大提高,通道平均Nu_m数最大可提高46%。比较了通道性能评价指标(Nu_m/Nu_(m0))/(f/f_0),综合性能三角翼优于矩形翼,对于三角翼布置方式不同对综合性能影响不大,对于矩形翼渐扩方式布置优于渐缩方式。纵向涡使速度与温度梯度的平均夹角减小,通道中流场和温度场协同程度得到改善。

3D numerical simulations are performed for laminar heat transfer and fluid flow characteristics of a fiat-plate channel with longitudinal vortex generators. The effects of two different type longitudinal vortex generators （LVGs）, rectangular winglet pairs （RWT） and delta winglet pairs （DWP）, with two different configurations, common-flow-down and common-flow-up, are examined. The Reynolds number based on the height of the channel varies from 190 to 1125. The numerical results show that the applications of the LVGs obviously enhance the heat transfer of the channel, the maximum enhancement of average Nusselt number is 46%. Compared by the performance evaluation parameter, （Nμm/Nμm0）/（f/f0）, the DWP shows a better overall performance than RWP, the common-flow-down and common-flow-up configurations of DWP have almost same overall performance, the common-flow-down configuration has a better overall performance than the common-flow-up configuration for RWP. The numerical results are also analyzed from the view point of field synergy principle, and it is found that the inherent mechanism of heat transfer augmentation by LVGs is that the secondary flow generated by LVGs results in the reduction of the intersection angle between velocity and temperature gradient.