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首页> 外文期刊>International Journal of Heat and Mass Transfer >Heat transfer augmentation of a channel flow by active agitation and surface mounted cylindrical pin fins
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Heat transfer augmentation of a channel flow by active agitation and surface mounted cylindrical pin fins

机译：通过主动搅拌和表面安装的圆柱销翅片增加通道流的传热

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With the intent of enhancing heat transfer, agitation of air flow is produced inside a high-aspect-ratio rectangular channel by means of a translationally oscillating plate. So that the test simulates channel flow between fins of a heat sink for cooling of electronics, the channel is open at one end, allowing oscillatory inflow and outflow at that end. At the other end where the roots of the fins that constitute the heat sink channel walls reside, there is a gap between the moving agitator plate and the channel base. Local heat transfer rates and velocity measurements are made within different regions of the channel. Heat transfer measurements are made on a channel wall augmented with cylindrical pin fins. They compared with equivalent measurement results taken on a smooth wall channel. An increase of 4-7%, based on total wetted area is found in the heat transfer coefficient, generally, when the pin fins are introduced. The change varies according to location within the channel, however. For instance, the heat transfer coefficient in the region near the base of the fins actually decreases 4-5% (again, based on total wetted area) when the pin fins are added. In this region, the flow passing through a tip gap between the agitator tip and the channel base wall, creates strong vorticity and high near-wall shear. These features of the flow are partially blocked by the pin fins, decreasing the effectiveness of the vorticity. Important to note in these comparisons, however, is that the pin fins offer an additional 30% heat transfer area. To help explain the observed trends, velocity measurements were taken with a single-component laser Doppler anemometer in the presence of pin fins as well as in the absence of pin fins. Pin fins lead to a loss of near-wall momentum but create greater mixing and three dimensionality of the near-surface flow.
机译：为了增强热传递，借助于平移振荡板在高纵横比矩形通道内产生气流的搅动。为了测试能够模拟散热器散热片之间的通道流动以冷却电子设备，通道的一端是开放的，那一端允许有振荡的流入和流出。在构成散热器通道壁的散热片根部所在的另一端，移动的搅拌板和通道底部之间存在间隙。在通道的不同区域内进行局部传热速率和速度测量。传热测量是在带有圆柱形针状翅片的通道壁上进行的。他们将其与在光滑墙壁通道上获得的等效测量结果进行了比较。通常，当引入针状翅片时，基于总润湿面积，传热系数增加了4-7％。但是，该变化根据通道内的位置而变化。例如，当添加针状翅片时，在翅片基部附近的区域中的传热系数实际上降低了4-5％（再次基于总润湿面积）。在该区域中，流过搅拌器尖端和通道底壁之间的尖端间隙的流动会产生强烈的涡流和高的近壁剪切力。流动的这些特征被针状翅片部分地阻挡，从而降低了涡旋的有效性。但是，在这些比较中要注意的重要一点是，针状散热片提供了额外的30％的传热面积。为帮助解释观察到的趋势，在存在针状鳍片或不存在针状鳍片的情况下，使用单分量激光多普勒风速计进行速度测量。针状鳍片会导致近壁动量的损失，但会产生更大的混合和近地表流动的三维性。

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