中文摘要：

以螺旋丁胞管为数值模拟对象,采用周期性边界条件,利用标准k-ε湍流模型和SIMPLE算法,研究了管内湍流的流动与传热性能。模拟结果表明,流体在流经丁胞前端时壁面附近有较大的径向速度分量,最大达主流速度的34.6%,有效地增强了湍流度。管内局部换热强度的分布对应于丁胞突起也呈周期性变化,最大换热系数是光管的2.48倍,而平均换热系数则是光管的1.7倍。丁胞的结构优化能使换热最大增强1.6-2.74倍,同时阻力系数（f/f0）^1/3增加1.54-1.63倍;丁胞的相对深度h/d存在的最优值在0.20-0.25之间;具有较小排列密度的丁胞管减阻效果更显著。以无量纲参数h/d、Re和D^2/pl拟合的Nu数和阻力系数f的关系式误差均在10%以内。

英文摘要：

Three-dimensional numerical simulations were investigated in order to obtain the heat transfer performance and pressure drop of the helically dimpled tubes.This computational model was built up by standard k—ε turbulent govern equation and SIMPLE algorithm with periodic boundary conditions.The results showed that the protrusion of dimples changed the magnitude and direction of the fluid flow,enhanced the turbulence intensity through flow interaction,and produce severe secondary flow.We could find that the maximum radial velocity amounted to 34.6% of mainstream velocity.The distribution of local heat transfer coefficient in the tube showed a cyclical change,corresponding to the cyclical dimples.The maximum and average heat transfer coefficient were enhanced by 2.48 times and 1.74 times,respectively,to that of a plain tube.The computed results indicated that the Nu for the helically dimpled tube was 60%-174% higher than that for the smooth tube,while the friction factors of the dimple tube increased by 54%-63% compared with the plain tube.The optimal value of dimple height h/d was between 0.20-0.25,and a tube with smaller dimple density was more significant in reducing pressure drop.The empirical formulas for Nu and /were fitted in terms of three non-dimensional parameters（dimple height h/d,dimple density D^2/pl,and Reynold number） based on calculation results.The maximum deviation of Nu and / were both controlled within 10%.