Experiments on turbulent natural convection in an enclosed tall cavity
Experiments on turbulent natural convection in an enclosed tall cavity
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DOI：
10.1016/s0142-727x(00)00033-3
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发表时间：
2000-12-01
影响因子：
2.6
通讯作者：
Bokhari, IH
中科院分区：
文献类型：
--
作者：
Betts, PL;Bokhari, IH
在一个高2.18 m，宽0.076 m，深0.52 m的高差热矩形空腔中进行了空气自然对流的实验研究。他们在垂直板之间的温差为19.6度和39.9度的情况下进行实验，得出基于0.86 x 10(6)和1.43 x 10(6)宽度的瑞利数。在这些条件下，腔体核心的流动完全是湍流的，性质随温度的变化相对较小。先前使用的实验装置已经过修改，通过安装部分传导的顶部和底部墙壁以及外部保护通道，以提供边界条件，避免温度梯度的不充分定义的急剧变化以及与名义绝热墙壁上的不充分绝缘相关的其他问题。测量了腔内的平均和湍流温度和速度变化，以及热通量和湍流剪应力。温度场和流场除了靠近前后壁面外，在腔体对角线上是不对称的。部分传导的顶板和底板在壁面射流中提供了局部不稳定的热分层，增强了气流向温控板移动时的湍流。研究结果为低湍流雷诺数湍流模型的测试提供了一个较好的基准。(C) 2000 Elsevier Science Inc.；版权所有。
Experiments have been undertaken to investigate the natural convection of air in a tall differentially heated rectangular cavity (2.18 m high by 0.076 m wide by 0.52 m in depth). They were performed with temperature differentials between the vertical plates of 19.6 degreesC and 39.9 degreesC, giving Rayleigh numbers based on the width of 0.86 x 10(6) and 1.43 x 10(6). Under these conditions the flow in the core of the cavity is fully turbulent and property variations with temperature are comparatively small. A previously used experimental rig has been modified, by fitting partially conducting top and bottom walls and outer guard channels, to provide boundary conditions which avoid the inadequately defined sharp changes in temperature gradient and other problems associated with insufficient insulation on nominally adiabatic walls. Mean and turbulent temperature and velocity variations within the cavity have been measured, together with heat fluxes and turbulent shear stresses. The temperature and flow fields were found to be closely two-dimensional, except close to the front and back walls, and anti-symmetric across the diagonal of the cavity. The partially conducting roof and floor provide locally unstable thermal stratification in the wall jet flows there, which enhances the turbulence as the flow moves towards the temperature controlled plates. The results provide a greatly improved benchmark for the testing of turbulence models in this low turbulence Reynolds number flow. (C) 2000 Elsevier Science Inc. All rights reserved.