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首页> 外文学位 >NATURAL CONVECTION IN A RECTANGULAR CAVITY DRIVEN BY COMBINED BUOYANCY FORCES.
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NATURAL CONVECTION IN A RECTANGULAR CAVITY DRIVEN BY COMBINED BUOYANCY FORCES.

机译：由组合浮力驱动的矩形腔中的自然对流。

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摘要

The objective of this study was to obtain an understanding of the flow, heat and mass transfer processes in a rectangular cavity. In a gravity field the simultaneous temperature and concentration differences lead to buoyancy driven convection. To this end, an analytical and numerical study of the problem was conducted.;The results show that the heat and mass transport through the cavity is enhanced when the buoyancy forces due to temperature and concentration are augmenting one another for the stability parameter N 2. Close to N = 1, flow reversal takes place for all of the ranges of the parameters considered here. It was also found that the local Nusselt numbers and the local wall velocities are proportional to one another for all the cases considered. The concentration parameter (GAMMA) had a significant effect on the wall velocities but a relatively small effect on the heat transfer. Multicellular flow structures have been predicted for the low Prandtl number mixtures, and the reasons for their formation have been discussed. The thermophysical property variation with temperature is shown to be significant, especially when the temperature gradients across the cavity are large. Results based on constant thermophysical properties in general yield higher heat and mass transport through the cavity. The inclusion of Soret and Dufour effects indicates that both the heat and mass transport are reduced for the ranges of parameters considered.;The study is concerned with the development of a model to predict the velocity, temperature and species distributions inside a two-dimensional, rectangular cavity filled with a binary gas. The transport equations of mass, species, momentum and energy are formulated in dimensionless form and are solved numerically. The work examines the transient and steady behavior of the flow structure as well as the total heat and mass transfer through the cavity. In addition consideration is given to the effect of the variation of thermophysical properties with temperature and mass fraction, including the Soret and Dufour effects. The predicted results have been tested extensively by comparison with well established benchmark solutions for the limiting case of pure thermal convection in cavities as well as other results available in the literature. A sensitivity study of the relevant dimensionless parameters was then performed to gain an understanding of the fundamental phenomena involved.
机译：这项研究的目的是了解矩形腔体中的流动，传热和传质过程。在重力场中，温度和浓度的差异同时导致浮力驱动的对流。为此，对该问题进行了分析和数值研究。结果表明，对于稳定性参数N 2，当温度和浓度引起的浮力相互增大时，通过腔的热量和质量传递会增加。接近N = 1时，此处考虑的所有参数范围都会发生逆流。还发现，在所有考虑的情况下，局部Nusselt数与局部壁速是成比例的。浓度参数（GAMMA）对壁速度有显着影响，但对热传递的影响相对较小。预测了低普朗特数混合物的多细胞流动结构，并讨论了其形成的原因。随温度变化的热物理性质显示出显着的变化，尤其是在整个腔体的温度梯度较大时。通常，基于恒定的热物理性质的结果会产生更高的热量和通过模腔的传质。 Soret和Dufour效应的纳入表明，在所考虑的参数范围内，传热和传质均降低。；该研究与模型的发展有关，该模型可预测二维内部的速度，温度和物种分布，充满二元气体的矩形腔。质量，物质，动量和能量的传输方程以无量纲形式表示，并用数值方法求解。这项工作检查了流动结构的瞬态和稳态行为，以及通过腔体的总热量和质量传递。另外考虑了热物理性质随温度和质量分数变化的影响，包括Soret和Dufour效应。通过与公认的基准解决方案进行比较，对预测结果进行了广泛的测试，这些解决方案适用于空腔中纯热对流的极限情况以及文献中提供的其他结果。然后对相关的无量纲参数进行敏感性研究，以了解所涉及的基本现象。

著录项

  • 作者

    PADMANABHAN, RANGANATHAN.;

  • 作者单位

    Purdue University.;

  • 授予单位 Purdue University.;
  • 学科 Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 1986
  • 页码 292 p.
  • 总页数 292
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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