EXPERIMENTAL DETERMINATION OF HEAT TRANSFER COEFFICIENTS IN WATER FLOWING OVER A HORIZONTAL ICE SHEET
EXPERIMENTAL DETERMINATION OF HEAT TRANSFER COEFFICIENTS IN WATER FLOWING OVER A HORIZONTAL ICE SHEET
复制标题
流过水平冰盖的水的传热系数的实验测定
DOI：
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发表时间：
1986
期刊：
影响因子：
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通讯作者：
Y. Yen
中科院分区：
文献类型：
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作者：
V. Lunardini;J. Zisson;Y. Yen
摘要：在横截面为1.2x1.2m、长35 m的冷冻水槽中进行了水平冰盖在水流作用下的融化实验。水深、温度和流速以及冰盖的温度和初始表面轮廓都是变化的。传热制度被发现包括强制湍流在高雷诺数与过渡到自由对流传热。没有令人信服的证据表明存在强迫层流状态。数据与每种状态相关，雷诺数Re或Grashof数与雷诺数结合为Gr/Re的2.5次方，用于表征不同类型的热传递。对于流过水平冰盖的水，只要水温超过3.4 ℃，在低流速下，融化热通量不会低于自由对流情况下的值-488.5 W/平方米。这是很重要的，因为自由对流融化值远远超过那些层流强制对流。在低流速下，熔化通量不依赖于流体温度，直到水温下降到3.4 ℃以下，当q sub c = 135.7（Δ T）。在一般情况下，传热被发现显着超过相同制度的非熔化系统。这是由于增加的自由流湍流，热不稳定性，由于水的密度最大值接近4 ℃，和湍流漩涡与波浪形的冰表面在融化过程中的产生。
Abstract : Experiments to study the melting of a horizontal ice sheet with a flow of water above it were conducted in a 35 m long refrigerated flume with a cross section of 1.2x1.2 m. Water depth, temperature, and velocity were varied as well as the temperature and initial surface profile of the ice sheet. The heat transfer regimes were found to consist of forced turbulent flow at high Reynolds numbers with a transition to free convection heat transfer. There was no convincing evidence of a forced laminar regime. The data were correlated for each of the regimes, with the Reynolds number, Re, or the Grashof number combined with the Reynolds number as Gr/Re to the 2.5 power used to characterize the different kinds of heat transfer. For water flowing over a horizontal ice sheet, the melting heat flux, for low flow velocities, was not found to drop below the value for the free convection case-488.5 W/sq m-as long as the water temperature exceeds 3.4 C. This is significant since the free convection melt values far exceed those for laminar forced convection. At the low flow velocities, the melting flux was not dependent upon the fluid temperature until the water temperature dropped below 3.4 C, when q sub c = 135.7 (Delta T). In general, the heat transfer was found to significantly exceed that of non-melting systems for the same regimes. This was attributed to increased free stream turbulence, thermal instability due to the density maximum of water near 4 C, and the turbulent eddies associated with the generation of a wavy ice surface during the melting.