Mixed Convection in the Cusped Duct
Mixed Convection in the Cusped Duct
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尖角管道中的混合对流
DOI：
10.1115/1.2910869
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发表时间：
1994
影响因子：
--
通讯作者：
M. Ebadian
中科院分区：
文献类型：
--
作者：
Z. Dong;M. Ebadian
在压水堆发生失水事故时，由于包壳两侧的压力差和堆芯温度的升高，燃料棒包壳会发生膨胀。在这种情况下，相邻的燃料棒可能会膨胀，直到它们与它们的邻居接触，导致子通道流动面积的减少和堵塞区域中的堆芯传热的恶化。这种阻塞可以看作是一个具有四个角的尖瓣管道，由四根直径相等的杆组装而成，如图1所示。因此，为了更好地设计紧急堆芯冷却系统（ECCS），必须充分了解这种管道中的流体流动和传热行为。一般来说，除了强制对流在尖角管道，自然对流由于高温的包层是一个重要的因素影响传热行为。一个广泛的调查文献处理的尖管显示，有一个有限的调查，在这方面的研究。古恩和达林（1963）测量了在尖形管道中层流、转捩和紊流范围内的摩擦系数。Gerard和Baines（1977）用实验方法研究了在尖形管道中紊流的速度和边界剪应力分布。Turner和Hague（1983）对压水反应堆堆芯内的流体流动和传热进行了实验研究，同时将结果与尖形管道内流动和传热的计算研究进行了比较。Hague等人（1982）采用了巴罗等人的阻尼混合长度湍流模型。（1978）来预测尖形渠道中充分发展的水流条件。哈桑和巴罗（1984）也用数值方法研究了四个尖角通道中的紊流。此外，他们还考虑了包层的厚度，并在他们的计算中使用的Ke两方程湍流模型。Maliska和Silva（1986）应用边界拟合坐标系（BFCS）来模拟层流和传热。他们举例说明了非正交和正交网格对解的影响。最近，Duck和Turner（1987）在燃料-包壳界面处施加了均匀热流条件，并在其分析中包括了包壳的厚度。Dong等人（1991）对各种尖形管道中的热发展流动进行了数值研究。此外，数字再-
In the unlikely event of a loss of coolant accident (LOCA) in a pressurized water reactor, the fuel rod cladding may swell due to a combination of pressure difference across the cladding and increase of the temperature level in the core. In this case, adjacent fuel rods may balloon until they make contact with their neighbors, leading to a reduction in the subchannel flow area and a worsening of the core heat transfer in the region of the blockage. This blockage can be visualized as a cusped duct with four corners formed by assembling four rods of equivalent diameters, as seen in Fig. 1. Therefore, for better design of the emergency core cooling system (ECCS), it is imperative that the behavior of fluid flow and heat transfer in such a duct is fully understood. Generally, except for the forced convection in the cusped duct, natural convection due to the high temperature of the cladding is a significant factor affecting heat transfer behavior. An extensive survey of literature dealing with the cusped duct reveals that there has been a limited number of investigations in this area of research. Gunn and Darling (1963) measured the friction factor for a range of laminar, transition, and turbulent flow in the cusped duct. Gerard and Baines (1977) experimentally investigated the velocity and boundary shear stress distributions for turbulent flow in a cusped duct. Turner and Hague (1983) performed an experimental study of fluid flow and heat transfer in the core of a pressurized water reactor, and at the same time they compared the results with a computational study for flow and heat transfer within the cusped duct. Hague et al.(1982) employed the damped mixed length turbulent model of Barrow et al.(1978) to predict the fully developed flow conditions in the cusped channel. Hassan and Barrow (1984) also numerically studied turbulent flow in a four-cusped channel. Furthermore, they also considered the thickness of the cladding, and the Ke two-equation turbulence model was used in their computation. Maliska and Silva (1986) applied a boundary-fitted coordinate system (BFCS) to simulate laminar flow and heat transfer. They illustrated the effects of nonorthogonal and orthogonal grids on the solution. Recently, Duck and Turner (1987) imposed a uniform heat flux condition at the fuel-cladding interface and included the thickness of the cladding in their analysis. Dong et al.(1991) conducted a numerical investigation of thermal developing flow in the various cusped ducts. In addition, numerical re-