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 The heat transfer by natural convection in an inclined rectangular enclosure with uniform volumetric energy sources has been studied through a MachZehnder interferometer and numerical analysis.When the enclosure is located with an angle of inclination, the flow patterns are unsymmetrical rolls; when the enclosure is located horizontally, an unstable stratification flow pattern is observed. The temperature and velocity fields are unsymmetrical due to the unsymmetry of flow patterns. The location... The heat transfer by natural convection in an inclined rectangular enclosure with uniform volumetric energy sources has been studied through a MachZehnder interferometer and numerical analysis.When the enclosure is located with an angle of inclination, the flow patterns are unsymmetrical rolls; when the enclosure is located horizontally, an unstable stratification flow pattern is observed. The temperature and velocity fields are unsymmetrical due to the unsymmetry of flow patterns. The location at which maximum temperature occurs is near y/H=0.8andx/w=0.9.The local and average heat transfer coeffioients are measured, the capacity of heat dissipation is different from Y=0 and Y =1 walls. The equations which correlate Nu_1/Nu。with Ra_1at different angles are obtained. The experimental and numerically predicted values are in good agreement.  本文对倾斜矩形腔内有均匀容积热源时的自然对流换热进行了实验研究和数值计算。研究表明,倾斜放置时,腔内流体出现不对称的涡流流动结构;水平放置时,腔内流体为不稳定的分层结构。由于流动结构的不对称,流体的速度和温度分布也不对称,腔内流体的最高温度出现在y/H=0.8、x/w=0.9附近。用光学干涉技术测定了沿恒温壁的局部和平均Nusselt数。结果表明,倾斜放置时,两恒温壁的热量散逸能力并不相同,拟合了不同θ时Nu_1/Nu_0与R_(?)的关联式。实验和数值计算结果吻合良好。  The paper regards the sedimentladen flow near the bed as a stratification flow resulting from concentration gradient,and analogizes the atmospheric stratification flow caused by temperature gradient.Citing the mixinglength of stratification flow.the paper has deduced the velocity of sedimentladen flow based on the equation of total tress force,then,the paper has deduced the mixinglength formula of sedimentladen flow.Flume materia shows the validity of the formula and the analogy... The paper regards the sedimentladen flow near the bed as a stratification flow resulting from concentration gradient,and analogizes the atmospheric stratification flow caused by temperature gradient.Citing the mixinglength of stratification flow.the paper has deduced the velocity of sedimentladen flow based on the equation of total tress force,then,the paper has deduced the mixinglength formula of sedimentladen flow.Flume materia shows the validity of the formula and the analogy of the sediment ladenflow to atmospheric stratification flow.  本文将挟沙水流近壁区视为由浓度梯度造成的层结流体，与大气边界层非中性平衡条件下温度梯度造成的层结流体相比拟．引入大气边界层的混掺长度作为挟沙水流近壁区的混掺长度．进而在从总切应力平衡式导出的流速梯度基础上，推导出挟沙水流沿整个水深的混掺长度公式，水槽资料证明了该公式的正确性以及挟沙水流近壁区与大气边界层的相似性．  Model similarityrules for confluence between a debris flow and the main river were analyzed, and a series of model experiments were performed to investigate the regularity of confluence between a debris flow and the main river. The experimental result shows that the movement patterns of a debris flow are different in the intersection region for different relationships between the branch and the main river and can be divided the submerging flow and the stratification flow. In the submerging flow,... Model similarityrules for confluence between a debris flow and the main river were analyzed, and a series of model experiments were performed to investigate the regularity of confluence between a debris flow and the main river. The experimental result shows that the movement patterns of a debris flow are different in the intersection region for different relationships between the branch and the main river and can be divided the submerging flow and the stratification flow. In the submerging flow, the velocity of the debris flow head, submerging into water, decreases approximately linearly, the changes in its height and length are very small, and there is a linear relationship between the width and the length. All these are quite different from a density current. Furthermore, when water flows into the branch, the debris flow head will be broken by water, resulting in the sedimentation of sand and stone. Under that condition, the debris flow entering into the river becomes a stratiform flow.  分析了泥石流与主河交汇试验的模型相似律并进行室内模型试验,探索了泥石流与主河水流的交汇规律.试验结果表明:交汇口支槽与主槽槽底之间的关系不同,泥石流入汇主槽后的运动形式也不同,大体可分为潜入式交汇和分层交汇2种形式.潜入式交汇中,泥石流龙头速度近似按线性关系衰减,龙头几何特征与异重流不同,它的高度与长度变化较小,横向宽度与长度可用线性关系表达;当支槽有回水时,泥石流头部受到水流的破坏,发生沙、石沉降,形成分层运动.   << 更多相关文摘 
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