In order to further improve the heat transfer performance inside tubes, a three-start twisted tube combined with oval dimples is proposed. The effects of dimple depths on the characteristics of fluid flow and heat transfer are numerically studied. The results indicate that the fluid mixing inside the tube is greatly improved by the longitudinal vortex generated behind the dimple compared with the corresponding three-start twisted tube without dimples. The maximum increases in Nusselt number and friction factor of the three-start twisted tube with dimples are 26.68% and 19.96% compared with the three-start twisted tube without dimples at Re = 2000, respectively. The maximum thermal performance factor of the three-start twisted tube with oval dimples is 1.19 compared with the three-start twisted tube without dimples. The thermal performance factor of the three-start twisted tube with oval dimples is up to 1.38 compared with the straight tube, which is larger than the reported twisted tubes, such as twisted tube, multi-start spirally corrugated tube, and twisted square duck reported in the open literature. The proposed three-start twisted tube with dimples provides a new choice for the heat transfer enhancement inside tubes.

为了进一步提高管内传热性能，提出了一种结合椭圆形凹坑的三头扭曲管。数值研究了凹坑深度对流体流动和传热特性的影响。结果表明，与相应的没有凹坑的三头扭曲管相比，凹坑后面产生的纵向涡流大大改善了管内的流体混合。带凹坑的三头扭管与无凹坑的三头扭管相比，在Re时努塞尔数和摩擦因数的最大增加分别为 26.68% 和 19.96% = 2000，分别。带椭圆形凹坑的三头双绞管与不带凹坑的三头双绞管相比，其最大热性能系数为1.19。带椭圆形凹坑的三头扭管与直管相比，热性能系数高达1.38，大于已报道的扭管、多头螺旋波纹管、扭方鸭等已报道的扭管。在公开文献中。提出的带凹坑的三头双绞管为管内强化传热提供了新的选择。