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首页> 外文期刊>International Journal of Heat and Mass Transfer >Large-eddy simulation of jet impingement heat transfer using a lobed nozzle
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Large-eddy simulation of jet impingement heat transfer using a lobed nozzle

机译：大叶喷嘴射流传热的大涡模拟

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摘要

The jet impingement heat transfer issuing from a lobed nozzle constructed using three circular orifices at a Reynolds number (Re) of 10,000 is investigated intensively with large-eddy simulation (LES). A comparative view was obtained for three nozzle configurations with different ratios of the orifice center offset (a) to the orifice radius (b) (i.e.,a/b = 0, 0.8, and 1.15) at two nozzle-to-wall distances (H/De = 2 and 4). A constant equivalent diameterDeis fixed for all of the configurations to ensure the nozzles’ constant cross-section area. Good agreement of the LES data with the results obtained with temperature-sensitive paint (TSP) and particle image velocimetry (PIV) is established for the azimuthal-averaged Nusselt number on the impingement wall and the velocity distributions in the wall-jet and impingement zones, respectively. For all three nozzle configurations atH/De = 2, the LES results delineate two heat removal mechanisms of the impinging jet. Near the second-peak circle, the heat transfer is enhanced by the secondary vortices near the wall, whereas beyond the second-peak circle the instantaneous flow impingement onto the wall plays a significant role in heat transfer enhancement. The secondary vortices and instantaneous flow impingement are strengthened significantly in the configuration witha/b = 0.8 atH/De = 2, giving rise to a substantial increase in the Nusselt number in the region 1 < r/De < 4. For the three configurations atH/De = 4, the instantaneous flow impingement is the main mechanism for heat transfer enhancement in the regionr/De < 0.5, whereas the increase ina/bresults in frequent activation of the intense flow impingement along with high turbulent kinetic energy, yielding better heat transfer on the heated wall.
机译：使用大涡模拟（LES）深入研究了由使用三个圆形孔构造的，有雷诺数（Re）为10,000的有瓣喷嘴产生的射流冲击传热。获得了三种喷嘴构造的比较视图，在两个喷嘴到壁的距离（即， H / De = 2和4）。所有配置都固定有一个恒定的等效直径De，以确保喷嘴的横截面积恒定。建立了LES数据与热敏涂料（TSP）和颗粒图像测速仪（PIV）的结果的良好一致性，以求出撞击壁上方位平均Nusselt数以及壁喷射和撞击区域中的速度分布， 分别。对于H / De = 2的所有三个喷嘴配置，LES结果描述了撞击射流的两种排热机理。在第二峰圆附近，壁附近的次级涡流增强了传热，而在第二峰圆以外，瞬时流撞击壁上在增强传热中起着重要作用。在H / De = 2处a / b = 0.8的配置中，次级涡旋和瞬时流动冲击得到了显着增强，在区域1

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