ABSTRACT

In this study, the effects of New Punched Rectangular Vortex Generators (NPRVGs) and Punched Rectangular Vortex Generators (PRVGs) inside a rectangular channel on heat transfer augmentation, Nusselt number, and friction factor were experimentally investigated. Temperature contours and average Nusselt numbers analyzed heat transfer characteristics resulting from the use of vortex generators. Furthermore, this study investigated the optimum values of the design parameters within the system of vortex generators by using the Taguchi method, and the orthogonal experimental plan was made for L₁₆ (4³x2¹). Reynolds numbers (5181, 10363, 20328, 25510), winglet arrangement, winglet attack angles (15°, 30°, 45°, 75°) and a distance of punched winglet from the channel bottom (b) to constant winglet height (e = 25 mm) (b/e = 0.04, 0.12, 0.2 and 0.36) were determined the working parameters in the experiments. Measurements are carried out for a rectangular channel with aspect ratio AR = 2, winglet transverse pitch (S) to longitudinal winglet height (e) ratio of S/e = 0.67 and a winglet height (e) to channel height (H = 25 mm) ratio of e/H = 1. Heat transfer rates of NPRVGs and PRVGs were compared to the obtained results for a smooth channel. The heat transfer performance is improved considerably by the NPRVGs. The maximum thermal performance factor increased from 0.99 to 1.89 owing to the combination of the vortex generator and the newly punched hole.

摘要

在这项研究中，实验研究了矩形通道内的新型冲孔矩形涡流发生器 (NPRVG) 和冲孔矩形涡流发生器 (PRVG) 对传热增强、努塞尔数和摩擦系数的影响。温度等值线和平均努塞尔数分析了使用涡流发生器产生的传热特性。此外，本研究采用田口法研究了涡流发生器系统内设计参数的最优值，并制定了L ₁₆ (4 ³ x2 ^{1 ) 的正交实验方案。}）。雷诺数（5181、10363、20328、25510）、小翼布置、小翼攻角（15°、30°、45°、75°）和冲压小翼从通道底部的距离（b）到恒定小翼高度（e = 25 mm) (b/e = 0.04, 0.12, 0.2 和 0.36) 确定了实验中的工作参数。测量长宽比 AR = 2、小翼横向螺距 (S) 与纵向小翼高度 (e) 比为 S/e = 0.67 和小翼高度 (e) 与通道高度 (H = 25 mm) 的矩形通道) e/H = 1 的比率。将 NPRVG 和 PRVG 的传热率与平滑通道的所得结果进行比较。NPRVG 显着提高了传热性能。由于涡流发生器和新冲孔的结合，最大热性能系数从0.99增加到1.89。