Geometrical parameters effect on turbulent flow field and heat transfer characteristics in a heat exchanger tube with tri-lobed cross section is numerically investigated. Three types of the tubes including twisted tube (TT), corrugated tube (CT) and corrugated twisted tube (CTT) are studied and compared in terms of thermohydraulic parameters. To capture the turbulent fluctuations over the range of Reynolds number from 4000 to 20,000, shear stress transport (SST) k-ω model is implemented into the code. In this study, the geometrical design variables consist of twist ratio, amplitude ratio, and wavelength ratio. According to the results, for the TT, the more the twist ratio, the greater the Nusselt number and friction factor. Due to the vortices generated by the centrifugal force in the CT, the mean Nusselt number in comparison with the smooth tube increases up to 80.5% at the wavelength ratio of 1/6. The results of the CTT show that the maximum value of performance evaluation criteria, 1.41, is obtained for this type of geometry at the twist ratio of 5, wavelength ratio of 1/6, and amplitude ratio of 0.75. These findings emphasize the advantage of simultaneously twisting and waving the tri-lobed tubes in intensification of the thermo-fluidic performances.

数值研究了几何参数对三叶形截面换热管内湍流场和传热特性的影响。对扭管（TT）、波纹管（CT）和波纹扭管（CTT）三种管子的热工水力参数进行了研究和比较。为了捕捉雷诺数从 4000 到 20,000 范围内的湍流波动，在代码中实施了剪切应力传递 (SST) k-ω 模型。在本研究中，几何设计变量包括扭曲比、幅度比和波长比。根据结果​​，对于TT，扭转比越大，努塞尔数和摩擦系数越大。由于 CT 中离心力产生的涡流，在波长比为 1/6 时，与光滑管相比，平均努塞尔数增加了 80.5%。CTT的结果表明，在扭曲比为5，波长比为1/6，幅度比为0.75时，这种几何形状获得了性能评估标准的最大值1.41。这些发现强调了同时扭曲和摆动三叶管在增强热流体性能方面的优势。