二维方腔内空气对流数值研究

发布时间：2018-03-18 08:32

本文选题：空气对流　切入点：平均努塞尔数　出处：《辽宁工程技术大学》2013年硕士论文　论文类型：学位论文

【摘要】：基于室内环境控制、污染物传播、设备散热或散湿等工程需要，，本文对二维方腔内空气对流问题展开了基础研究工作。首先，研究对流换热问题计算方法，将得出的平均努塞尔数Nu与基准解进行比较，误差均在1.00%以内，验证方法的正确性。进一步研究密度、导热系数、动力黏度、比热容、气体物性的不同处理方法对计算结果的影响，与已验证的计算方法所得Nu进行对比分析，得出：方腔内温差在30K以下，Boussinesq假设法计算误差小于1.50%；温差为500K时，误差可达9.30%；温差为500K时，常物性的计算方法相对于变物性最大相对误差为7.28%，应考虑气体物性随温度的变化。其次，采用组合温度尺度法研究方腔内具有离散热源/污染源的复杂传热传质问题。分别研究了浮升力比、间距以及热源强度等对流动结构的影响。再次，研究了高瑞利数下二维方腔内的空气对流情况。通过计算和验证得出：当Gr109时，应采用层流计算方法进行计算；当Gr109时，层流状态转变为湍流状态，用湍流计算方法得到的Nu更为准确。
[Abstract]:Based on the engineering requirements of indoor environmental control, pollutant propagation, equipment heat dissipation or moisture dissipation, the basic research work on two-dimensional air convection in square cavity is carried out in this paper. First of all, the calculation method of convection heat transfer problem is studied, the average Nussel number Nu is compared with the reference solution, the error is less than 1.00%, the correctness of the method is verified, and the density, thermal conductivity, dynamic viscosity and specific heat capacity are further studied. The effect of different treatment methods of gas physical properties on the calculation results is compared with the Nu calculated by the verified method. It is concluded that the calculation error of Boussinesq hypothesis method is less than 1.50 when the temperature difference is less than 30K, and the temperature difference is 500K. When the temperature difference is 500K, the maximum relative error of constant physical property is 7.28. The variation of gas physical property with temperature should be considered. Secondly, the combined temperature scale method is used to study the complex heat and mass transfer problem with discrete heat source / pollution source in the square cavity, and the effects of the floating lift ratio, the spacing and the heat source intensity on the flow structure are studied respectively. Thirdly, the air convection in a two-dimensional square cavity with high Rayleigh number is studied. The results of calculation and verification show that the laminar flow calculation method should be used for Gr109, and the laminar flow state should be changed to turbulent state when Gr109 is used. Nu obtained by turbulence calculation method is more accurate.
【学位授予单位】：辽宁工程技术大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU831;X51

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