Abstract: Based on the simplified physical models, fluid turbulent flow and heat transfer in the half-coil jackets were studied according to the numerical simulation by CFD software Fluent. The results indicate that on the cross perpendicular to helix, the contour shape of time average tangential velocity is saddle-backed and the velocity gradient near the outer curved wall is much greater than that near the inner straight wall. The steady flow structure of secondary flow is with two vortexes and the centers of the two-vortex locate near the sharp points of semicircular cross section. Affected by the secondary flow, the distribution of local Nusselt number is asymmetry on the heated straight wall with the minimum value locating at the center of heated wall and the maximum one locating at two sides of the center point. With the studied limit, the minimum is 0.8~0.85 and maximum 1.15~1.25 times of average value. The dimensionless pitch has a slight effect on the developed flow and heat transfer characteristic. With the increase of curvature, the heat transfer in the jacket is enhanced and the flow resistance increased at the same time.

Key words: half-coil jacket, numerical simulation, turbulent flow, secondary flow, heat transfer enhancement

摘要： 应用CFD分析软件Fluent，在简化模型的基础上对螺旋半圆管夹套内的三维湍流流动及换热进行了数值模拟. 结果表明，夹套内与螺旋线垂直的横截面上，切线方向的时均速度等值线呈鞍状分布，弯曲外壁侧的速度梯度远大于直内壁侧；二次流为稳定的两涡结构，二次涡的中心位置在半圆形截面的2个尖角附近. 由于二次流的作用，换热壁面上局部努塞尔数Nulocal分布不均，最小值在壁面中心点处，最大值在中心点两侧，研究范围内，最小值为平均值的0.8~0.85倍，最大值为平均值的1.15~1.25倍. 螺距对夹套内充分发展段的流体流动及换热的影响很小；增大曲率，夹套的换热能力增强，同时流动阻力也增大.

关键词: 螺旋半圆管夹套, 数值模拟, 湍流, 二次流, 强化换热