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不同高宽比的矩形空腔内流体浮升流动特性分析张娇娇,赵忠超,成华,丰威仙 (江苏科技大学能源与动力工程学院，江苏 镇江 212003)摘 要：本文应用无量纲分析方法，建立了矩形空腔内流体浮升流动的数学模型，研究了相同工况下不同高宽比对其流动换热的影响。研究结果表明：不同高宽比对流体的浮升流动具有较大影响，随着高宽比的增大，空腔内流体流动的层流过渡层向Ra值减小的方向偏移，且当Ra数一定时，Numean随高宽比迅速地达到最大值后缓慢减小；随着Ra值的增加，空腔中涡的数量逐渐增加，浮升流动强度增大，Numean增大，且Numean的最大值向高宽比减小的方向偏移。关键词：矩形空腔；高宽比；浮升流动；数值模拟中图分类号：TK 124 文献标志码：A 文章编号：The Flow Characteristics of Free Fluid Driven by Buoyancy in Rectangular Cavity with Different Aspect RatioZhao Zhong-chao, Zhang Jiao-jiao, Chen Hua, Feng Wei-xian (School of Energy and Power Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003)Abstract：In this paper, the mathematic model of buoyant lift flow in a rectangular cavity was developed by the dimensionless analytical method. The effects of rectangular cavity with different aspect ratio on the heat convection were simulated and analyzed through this mathematic model under same working condition. The results show that: the aspect ratio of rectangular cavity has great effects on the character of buoyant lift flow and heat convection efficiency. With the aspect ratio increased, the transition layer of laminar flow has the changing tendency to the Rayleigh number decreasing. When the Rayleigh number keeps constant, the average Nusselt number dramatically approach to the maximum and then evenly decrease. The eddies amount, intensity of buoyant flow and average Nusselt number has increased with the Rayleigh number enlarged. The maximum of average Nusselt number also has the changing tendency to the aspect ratio decreasing.Keywords: rectangular cavity; aspect ratio; buoyant flow; numerical simulation1.引言封闭空腔内的流体浮升流动因其具有安全、经济和无噪声等优点被广泛地应用于不同的工业冷却技术领域，如不用风扇强制冷却的电子设备的散热、事故条件下核反应堆的散热、平板式太阳能集热器的空气间层中的散热等。同时，流体浮升流动的机理及其变化规律也获得了大量研究人员的关注，De Vahl Davis G[1-2]最早发表了封闭方腔流体浮升对流换热问题的基准解。近年，Mina Shahi[3]等人研究了纳米流体对腔内浮升对流换热的强化作用，与此同时J. Serrano-Arellano[4]等学者研究了空腔内流体为空气和二氧化碳混合物时的自然对流换热的变化规律。也有Yang Liu[5]和K. Kalidasan[6]等人对加了翅片和挡板的腔内自然对流换热进行了研究和总结。国内如董韶峰等人[7] 利用涡量-流函数方程对非正方形的矩形空腔内的