Abstract

In this article, the effects of convex dimple streamwise arrangements on the flow and heat transfer characteristics of protrusion-grooved channels are determined, and five streamwise positions of convex dimples are considered. In addition, research on the transverse-circular-protrusion-grooved channel is also performed to serve as a contrast. The results indicate that replacing the transverse-circular-protrusion with the convex dimple produces a counter-rotating vortex pair, and the streamwise arrangements of the convex dimple significantly affect the flow structure downstream of the convex dimples. As the convex dimple is moved downstream, the velocities near the center protrusion-grooved surface increase till a maximum occurs for the case of a convex dimple placed at the center between adjacent grooves, and then decrease. Compared with the case of transverse-circular-protrusion, the convex dimple at the center region can enhance the overall heat transfer rate, while if it approaches the adjacent grooves lower heat transfer rate appears. Besides, replacing the transverse-circular-protrusion with the convex dimple can significantly reduce the pressure loss penalty and enhance the thermal performance factor. In addition, the effect of streamwise arrangements of convex dimples on the friction factor is slight, but the case with the center convex dimple exhibits the best overall thermal performance.

摘要

在本文中，确定了凸凹坑的流向布置对凸出槽形通道的流动和传热特性的影响，并考虑了凸凹坑的五个流向位置。另外，还进行了关于横向圆形突起沟槽的研究，以作为对比。结果表明，用凸状凹痕代替横向圆形凸起会产生反向旋转的涡流对，凸状凹痕的流向排列会显着影响凸状凹痕下游的流动结构。随着凸凹窝向下游移动，凸凹窝位于相邻凹槽之间的中心的情况下，中心凸出凹槽表面附近的速度会增加，直到出现最大值，然后降低。与横向圆形凸起的情况相比，中心区域的凸起凹窝可以提高整体传热速率，而如果它接近相邻的凹槽，则传热速率会降低。此外，用凸凹窝代替横向圆形凸起可以显着减少压力损失损失并提高热性能系数。另外，凸凹窝的沿流方向布置对摩擦系数的影响很小，但是具有中央凸凹窝的情况显示出最佳的整体热性能。用凸凹痕代替横向圆形凸起可以显着减少压力损失损失并提高热性能系数。另外，凸凹窝的沿流方向布置对摩擦系数的影响很小，但是具有中央凸凹窝的情况表现出最佳的整体热性能。用凸凹痕代替横向圆形凸起可以显着减少压力损失损失并提高热性能系数。另外，凸凹窝的沿流方向布置对摩擦系数的影响很小，但是具有中央凸凹窝的情况显示出最佳的整体热性能。