辐射—导热耦合传热下复合材料当量导热性能研究

发布时间：2018-06-02 03:40

本文选题：碳纤维 + 格子Boltzmann方法　；参考：《哈尔滨工业大学》2015年硕士论文

【摘要】：碳纤维复合材料具有的低热导率性能使得它在热防护方面的用途越来越广泛,而且任何高于绝对零度的物体都在发射和吸收辐射能,尤其在高温情况下。格子Boltzmann方法在流体力学与热传输领域目前是最具前途的数值模拟方法之一,对辐射与导热耦合传热问题的研究也具有可行性。本文从理论出发,基于格子Boltzmann方法对碳纤维复合材料的五种典型结构进行了导热和辐射导热耦合模拟,针对90°二维编织、短切纤维无规则排列、轴向相互平行排列等典型编织结构,及有规则光滑层状组织、各向同性光滑层状组织、粗糙层状组织等三类热解碳微观组织,主要研究内容包括:(1)基于格子Boltzmann方法,针对碳纤维复合隔热结构,建立了热传导模型,采用Fortran语言编制了导热及辐射的计算程序并进行了可靠性验证;(2)计算了从273K到1273K之间五种结构的各向异性导热性能,分析温度、厚度、编织结构和热解碳微观组织对其导热性能的影响;(3)计算五种结构辐射导热耦合传热下的当量传热性能参数,分析温度对辐射热流的影响规律,并分别对比辐射热流对不同编织结构和不同热解碳微观组织的碳纤维复合材料导热性能的影响程度。研究发现,碳纤维复合材料的温度、厚度、编织结构均对其传热性能有着明显的影响。考虑辐射作用下的当量传热性能,在低温时与纯导热相比差别不大,而在温度高于600K之后,当量传热性能逐渐高于纯导热的值,为工程应用提供了设计参考。
[Abstract]:Carbon fiber composites are widely used in thermal protection due to their low thermal conductivity, and any object above absolute zero emits and absorbs radiation energy, especially at high temperature. Lattice Boltzmann method is one of the most promising numerical simulation methods in the field of fluid mechanics and heat transfer. In this paper, based on lattice Boltzmann method, heat conduction and radiation conduction coupling simulation of five typical structures of carbon fiber composites are carried out. For 90 掳two-dimensional braiding, the short cut fibers are arranged irregularly. Typical braided structures such as axial parallel arrangement, regular smooth lamellar structure, isotropic smooth lamellar microstructure, rough lamellar microstructure, etc. The main research contents include: 1) lattice Boltzmann method. A heat conduction model is established for carbon fiber composite thermal insulation structure. The calculation program of heat conduction and radiation is compiled by Fortran language and the reliability verification is carried out. The anisotropic thermal conductivity of five structures from 273K to 1273K is calculated, and the temperature is analyzed. The influence of thickness, braided structure and Microstructure of Pyrolytic carbon on the Thermal conductivity of five structures the equivalent heat transfer performance parameters under the radiation heat conduction coupling are calculated, and the influence of temperature on the radiation heat flux is analyzed. The effects of radiation heat flux on the thermal conductivity of carbon fiber composites with different braided structures and different pyrolytic carbon microstructures were compared. It is found that the temperature, thickness and braided structure of CFRP have obvious influence on the heat transfer performance. Considering the effect of radiation, the equivalent heat transfer performance is not different from that of pure heat conduction at low temperature, but when the temperature is above 600K, the equivalent heat transfer performance is gradually higher than that of pure heat conduction, which provides the design reference for engineering application.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB33

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