涡发生器结构对螺旋通道传热和熵产的影响

为考察恒热流密度时不同形状涡发生器对螺旋通道内流体湍流状态下传热特性的影响，采用RNG K-ε湍流模型，对内壁光滑以及内置体积相同的半球形、圆柱形和圆锥形涡发生器的螺旋通道进行数值模拟。在工质为常温水，热流密度为50 000 W/m2，入口温度为298 K，入口速度范围为0.5~1.0 m/s的条件下，研究了湍流状态下4种螺旋通道的 努赛尔数、泊肃叶数和综合性能评价因子（η），并根据热力学第二定律进行熵产计算。结果表明：在湍流状态下，3种涡发生器对努塞尔数的影响不大，泊肃叶数有所增加，η均小于且接近1，总熵产提高，并随雷诺数的增加而减小。综上可知，涡发生器结构的改变对螺旋通道的传热效果影响较小，对熵产提升显著。

Effect of Different Structure of Vortex Generators on Heat Transfer and Entropy Generation in Helical Channel

In order to study the effect of different vortex generators under constant heat flux on heat transfer and entropy generation of the fluid that in the turbulent state in helical channel, a numerical study was carried out to investigate smooth-wall helical channel with same volume of vortex generators of hemisphere, cylinder and cone by using RNG K-E turbulence model. The condition of the simulation includes an inlet temperature of 298 K, the inlet velocity ranges from 0. 5 m/s t0 1. 0 m/s, heat flux of 50 000 W/m2 , and the working fluid is room temperature water. Under this condition, nusselt number, poiseuille number and performance evaluation criterion ( 77) of the four kinds of helical channels had been studied, and their entropy generation had been calculated with the second law of thermodynamics under turbulent state. The result shows that, under turbulent state, three kinds of vortex generators had little effect on the nusselt number, poiseuille number mcreased, and values of 77 are close to and less than l, the total entropy generation increased, and decreased with the increase of reynolds number. In conclusion, the change of the structure of the vortex generators in helical channel had little effect on heat transfer, but the entropy generation increased significantly.