Boundary layer theory approach to the concentration layer adjacent to a ceiling wall of a hydrogen leakage: Far region
Boundary layer theory approach to the concentration layer adjacent to a ceiling wall of a hydrogen leakage: Far region
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DOI：
10.1016/j.ijhydene.2008.09.047
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发表时间：
2008-12
影响因子：
7.2
通讯作者：
M. El-Amin;M. Inoue;H. Kanayama
中科院分区：
文献类型：
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作者：
M. El-Amin;M. Inoue;H. Kanayama
根据氢气浓度分布和流动特性的重要性，可以将部分开放空间氢气泄漏场划分为两个主要区域。这两个区域分别是靠近空间顶壁的射流区域和附面层区域，它们是由氢射流撞击壁面而形成的。根据流动的建模，边界层区域又可分为两个区域。这些区域是停滞点边界层区域和远边界层区域。在此之前，我们研究了停滞点流动区域（Hiemenz流动）[El-Amin MF, Kanayama H.]。[J]氢能源，出版中。本文利用边界层理论对顶板附近的边界层远区进行了分析。同时，对部分开放空间的氢气泄漏进行了实验，估计了天花板下区域中心的垂直浓度分布。为了验证边界层理论的方法，将测量结果与边界层理论的近似结果进行了比较，结果显示出很好的一致性。计算了顶墙的剪力、局部摩擦系数、摩擦阻力和无因次阻力系数。同时，估计了动量边界层和浓度边界层的厚度。
The field of the hydrogen leakage in partially open space can be divided into two main regions according to the importance of the hydrogen concentration distribution and the flow behavior. These two regions are the jet region and the boundary layer region which are adjacent to the ceiling wall of the space, resulting from impinging the hydrogen jet to the wall. The boundary layer region in turn can be divided into two regions, according to the modeling of the flow. These regions are the stagnation-point boundary layer region and the far boundary layer region. Previously, we studied the region of stagnation-point flow (Hiemenz flow) [El-Amin MF, Kanayama H. Boundary layer theory approach to the concentration layer adjacent to a ceiling wall at impinging region of a hydrogen leakage. Int J Hydrogen Energy, in press.]. The current paper is devoted to analyze the far region of the boundary layer adjacent to the ceiling wall using the boundary layer theory. Also, an experiment has been conducted on the hydrogen leakage in partially open space to estimate the concentration distribution vertically at the center of the domain under the ceiling wall. In order to verify the boundary layer theory approach, a comparison between the measurements and the boundary layer theory approximations is investigated and the results showed a good agreement. The wall shear stress, the local friction factor, the friction drag and the non-dimensional drag coefficient of the ceiling wall are calculated. Also, both momentum and concentration boundary layer thicknesses are estimated.