螺旋半圆管夹套内层流流动及换热特性研究

将螺旋半圆管夹套的物理模型简化为半圆形截面螺旋管,对4种不同结构夹套内的三维层流流动及换热进行了模拟求解,所得的结果与文献中的实验数据进行了对比。给出了发展段以及充分发展段的流场和温度场的分布,通过坐标变换得到了二次流的矢量图;分析了雷诺数Re、量纲一曲率δ和量纲一螺距λ对夹套内流体流动及换热特性的影响。结果表明:二次流对螺旋半圆管夹套的换热起强化作用,λ的影响很小,仅增大,δ流动阻力及壁面平均努塞尔数Nu均增大。

Laminar flow and heat transfer characteristic in half-coiled jacket

The physical model of half-coiled jacket was simplified to helical tube with semicircular cross.The numerical simulations on the three-dimensional laminar flow and heat transfer in four kinds of half-coiled jackets were performed and the results were contrasted with the experimental data in the literature.The developing and fully developed flow and temperature fields were given.By using coordinate transformation,the vector diagram of secondary flow was obtained.The effects of Re number,dimension one curvature δ and dimension one pitch λ on the flow and heat transfer characteristics inside jacket were analyzed.The results show that the secondary flow can enhance the heat transfer in half-coiled jacket.The effect of λ is very little.With the increase of δ,the flow resistance and the wall average Nu number are both enhanced.