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首页> 外文会议>ASME(American Society of Mechanical Engineers) Turbo Expo vol.4 pt.A; 20070514-17; Montreal(CA) >LES Investigation of Flow and Heat Transfer in a Channel with Dimples and Protrusions
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LES Investigation of Flow and Heat Transfer in a Channel with Dimples and Protrusions

机译：LES研究带凹痕和突起的通道中的流动和传热

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摘要

LES calculations are conducted for flow in a channel with dimples and protrusions on opposite walls with both surfaces heated at three Reynolds numbers, Re_H = 220, 940, and 9300 ranging from laminar, weakly turbulent to fully turbulent, respectively. Turbulence generated by the separated shear layer in the dimple and along the downstream rim of the dimple is primarily responsible for heat transfer augmentation on the dimple surface. On the other hand, augmentation on the protrusion surface is mostly driven by flow impingement and flow acceleration between protrusions, while the turbulence generated in the wake has a secondary effect. Heat transfer augmentation ratios of 0.99 at Re_H=220, 2.9 at Re_H=940, and 2.5 at Re_H=9300 are obtained. Both skin friction and form losses contribute to pressure drop in the channel, with form losses increasing from 45% to 80% with an increase in the Reynolds number. Friction coefficient augmentation ratios of 1.67, 4.82 and 6.37 are obtained at Re_H=220, 940, and 9300, respectively. Based on the geometry studied, it is found that dimples and protrusions may not be viable heat transfer augmentation surfaces when the flow is steady and laminar.
机译：LES计算针对的是在相对壁上具有凹坑和突起的通道中的流动，两个表面的加热温度分别为层流，弱湍流到完全湍流的三个雷诺数，Re_H = 220、940和9300。在凹痕中以及沿着凹痕的下游边缘由分离的剪切层产生的湍流主要负责在凹痕表面上的传热增加。另一方面，突起表面上的增大主要由突起之间的流动冲击和流动加速度驱动，而尾流中产生的湍流具有次要作用。获得的传热增强比在Re_H = 220时为0.99，在Re_H = 940时为2.9，在Re_H = 9300时为2.5。皮肤摩擦和形式损失均导致通道中的压力下降，随着雷诺数的增加，形式损失从45％增加至80％。在Re_H = 220、940和9300时分别获得1.67、4.82和6.37的摩擦系数增大比。根据研究的几何形状，发现在流动稳定且呈层流状态时，凹坑和突起可能不是可行的传热增强表面。

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