The thermal enhancement and pressure drop in a circular tube with radially-arrayed winglet vortex generator (VG) mounted inside at different orientations were experimentally studied. A series of four winglet rings containing VGs were on the inner surface of the tube at different sections. The effects of winglet attack angles β (0–45°), pitch ratios PR (1.6–4.8), porosity ratio γ (0–20%), winglet length L (10–20 mm), and inclination angle α (0–30°) on heat transfer and pressure drop characteristics were carefully examined. The study was carried out at Reynolds numbers (Re) ranging from 6 × 10³ to 2.7 × 10⁴ nestling in the turbulent flow regime. Results showed a significant effect of the winglets on the heat transfer enhancement and pressure penalty compared to the smooth tube. Experiments further revealed that as the length or attack angle of winglets increased, both Nusselt number (Nu) and friction factor (f) were intensified. When it turned to pitch ratio and inclination angle of winglets, the trend became adverse. By comparing the contribution of different winglet parameters, it is preferable to optimize the pitch ratio (PR) other than length, inclination angle (α) nor attack angle (β) for a higher thermal enhancement. The case of small porosity ratio (γ = 10%) at a low Re yields the maximum thermal enhancement of 1.26. Empirical correlations for Nu and f were generated for the winglets based on experimental data.

实验研究了圆形管内径向排列的小翼涡流发生器（VG）在不同方向安装时的热增强和压降。一系列包含VG的四个小翼环位于管的内表面不同部位。小翼迎角β（0–45°），螺距比PR（1.6–4.8），孔隙率γ（0–20％），小翼长度L（10–20 mm）和倾斜角α（0–0仔细检查30°）的传热和压降特性。该研究是在雷诺数（Re）为6×10 ³到2.7×10 ^{4的情况下进行的}处于湍流状态。结果显示，与光滑管相比，小翼对传热增强和压力损失有显着影响。实验进一步表明，随着小翼的长度或攻角的增加，努塞尔数（Nu）和摩擦系数（f）都增强了。当转向小翼的螺距比和倾斜角时，这种趋势变得不利。通过比较不同的小翼参数的贡献，优选地除了长度，倾斜角（α）或迎角（β）以外，优化桨距比（PR），以获得更高的热增强。孔隙率低（γ  = 10％）低时Re产生的最大热增强值为1.26。基于实验数据，为小翼生成了Nu和f的经验相关性。