基于热流固耦合的微型换热器设计方法研究

发布时间：2018-07-05 18:30

本文选题：微型换热器 + 热流固耦合　；参考：《南昌大学》2015年硕士论文

【摘要】：以整体微通道换热器为研究对象的流体流动传热和结构热应力的有限元数值模拟方法均面临有限单元数过多诱发的通用计算机计算能力不够的限制,从而使微通道换热器结构应力模拟仿真至今仍是一项工程技术挑战,针对这一技术难题,本文研究提出了通过在对称单元位移边界施加等效弹性支撑约束来近似反映微通道壁面的热胀冷缩的位移约束的简化模拟技术方法,并实现了微通道换热器传热和结构应力的快速模拟,为微通道换热器计算机辅助工程虚拟样机设计奠定了基础。本文基于对称单元位移边界施加等效弹性支撑约束的简化模拟技术方法,模拟研究了不同微通道换热器的流阻特性、传热特性和结构强度特性,为研发高效微通道换热器提供了理论指导。研究主要取得如下成果:在微通道换热器中截取对称单元方法不能直接用于结构应力模拟仿真,而采用整体微型换热器为对象的结构应力模拟仿真又面临计算机计算能力的限制,所以微通道换热器结构应力模拟仿真至今仍是一项工程技术挑战,而研究提出基于对称单元的微通道换热器结构应力的有限元简化模拟分析法是解决这一技术难题的关键。针对上述技术难题,本文首次研究提出了通过在对称单元位移边界施加等效弹性支撑约束来近似反映微通道壁面的热胀冷缩的位移约束的微通道换热器危险区域热流固耦合热应力的有限元简化数值模拟方法。基于对称单元施加等效弹性约束的有限元简化数值模拟方法系统研究了不同微通道换热器的流阻特性、传热特性和结构强度特性,研究结果表明微通道换热器流阻压降从大到小排序为:三角形微通道?六边形微通道?矩形微通道?椭圆形微通道?圆形微通道;冷流体实际被加热效果从大到小排序为:三角形微通道?矩形微通道?六边形微通道?椭圆形微通道?圆形微通道。传热速度从大到小的排序为:椭圆形微通道?圆形微通道?六边形微通道?矩形微通道?三角形微通道,结构强度从高到低排序为:三角形微通道?矩形微通道?六边形微通道?圆形微通道?椭圆形微通道。
[Abstract]:The finite element numerical simulation method of fluid flow heat transfer and structural thermal stress, which is based on the whole microchannel heat exchanger, faces the limitation of the general computer computing ability caused by the excessive number of finite elements. Therefore, the stress simulation of microchannel heat exchanger structure is still a technical challenge. In this paper, a simplified simulation technique is proposed to approximate the displacement constraints of thermal expansion and contraction on the wall of microchannels by imposing equivalent elastic support constraints on the displacement boundary of symmetric elements. The fast simulation of heat transfer and structural stress of microchannel heat exchanger is realized, which lays a foundation for the computer aided engineering virtual prototype design of microchannel heat exchanger. In this paper, the flow resistance, heat transfer and structural strength characteristics of different microchannel heat exchangers are simulated based on the simplified simulation method with equivalent elastic bracing constraints imposed on the displacement boundary of symmetric elements. It provides theoretical guidance for the research and development of high efficiency microchannel heat exchanger. The main achievements are as follows: the method of intercepting symmetric elements in microchannel heat exchangers can not be directly used in structural stress simulation. However, the simulation of structural stress with the whole micro heat exchanger is faced with the limitation of computer computing ability, so the simulation of structural stress of microchannel heat exchanger is still a technical challenge in engineering up to now. The key to solve this technical problem is to propose a simplified finite element simulation method for structural stress of microchannel heat exchangers based on symmetric elements. In view of the technical difficulties mentioned above, In this paper, we present for the first time the thermal-fluid-solid coupling thermal stress in the dangerous region of microchannel heat exchanger by applying equivalent elastic support constraints on the displacement boundary of symmetric elements to approximate the displacement constraints of thermal expansion, cooling and contraction on the wall of the microchannel. Finite element simplified numerical simulation method. The flow resistance, heat transfer and structural strength characteristics of different microchannel heat exchangers are systematically studied by a simplified finite element numerical simulation method based on the equivalent elastic constraints imposed by symmetric elements. The results show that the order of pressure drop of flow resistance in microchannel heat exchanger from large to small is: triangular microchannel? Hexagonal microchannel? Rectangular microchannels? Oval microchannel? Circular microchannels; the actual heating effects of cold fluids are in order from large to small: triangular microchannels? Rectangular microchannels? Hexagonal microchannel? Oval microchannel? Circular microchannel. The order of heat transfer rate from large to small is: elliptical microchannel? Circular microchannels? Hexagonal microchannel? Rectangular microchannels? Triangular microchannels, structural strength from high to low order: triangular microchannel? Rectangular microchannels? Hexagonal microchannel? Circular microchannels? Oval microchannel.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051.5

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