本文選題：瞬態(tài)熱線法 + 數(shù)值模擬��； 參考：《華北電力大學(xué)(北京)》2016年碩士論文

【摘要】：瞬態(tài)熱線法是一種常用的熱物性測量方法,現(xiàn)已被推廣應(yīng)用于粉體、液體、復(fù)合材料、含濕多孔介質(zhì)、高溫下非透明和半透明固體等材料的導(dǎo)熱系數(shù)測量。鑒于瞬態(tài)熱線法的非穩(wěn)態(tài)測量的特點(diǎn),誤差估計(jì)一直是該類測試技術(shù)的難題。針對該類技術(shù),利用數(shù)值模擬進(jìn)行導(dǎo)熱系數(shù)測量誤差的分析更不多見。本文通過數(shù)值模擬對瞬態(tài)熱線法導(dǎo)熱系數(shù)的測量誤差進(jìn)行分析研究,分析各種因素對瞬態(tài)熱線法導(dǎo)熱系數(shù)測量誤差的影響規(guī)律。論文在論述瞬態(tài)熱線法測量的原理、模型和分類的基礎(chǔ)上,對其建立數(shù)學(xué)模型,并采用Fluent進(jìn)行數(shù)值模擬,得到溫度場分布及監(jiān)測點(diǎn)溫度值,根據(jù)理論公式得出導(dǎo)熱系數(shù)的模擬值,將模擬值與設(shè)定值進(jìn)行比較得到導(dǎo)熱系數(shù)的測量誤差。根據(jù)瞬態(tài)熱線法的原理及假設(shè),選取了不同的試樣尺寸、熱線半徑和熱線熱容進(jìn)行模擬,得到導(dǎo)熱系數(shù)的相對誤差隨不同參數(shù)變化的規(guī)律。研究結(jié)果表明,數(shù)值模擬得到的溫度場分布與理論分析相吻合。在其它參數(shù)一定時,測量誤差隨著試樣尺寸的減小而增大,隨著熱線半徑的增大而增大,隨著熱線熱容的增加而增大,且瞬態(tài)熱線法更適合測量導(dǎo)熱系數(shù)小的材料。當(dāng)試樣的尺寸w×b≥6.5 mm×16.5mm時,利用瞬態(tài)熱線法測得1.5W/(m·K)λ2.0 W/(m·K)的材料,導(dǎo)熱系數(shù)與設(shè)定的導(dǎo)熱系數(shù)之間的相對誤差可以保證在0.5%以內(nèi)；當(dāng)熱線半徑為r0=0.001mm時,導(dǎo)熱系數(shù)的測量誤差的增長量很小,增長量僅為0.029%,基本不隨熱線熱容的變化而變化；當(dāng)熱線半徑小于0.006mm時,如果被測試樣的導(dǎo)熱系數(shù)γ=0.1W／(m-K),相對誤差的增長量很小,幾乎不變,基本可以忽略。因此利用瞬態(tài)熱線法測量材料的導(dǎo)熱系數(shù)時,為提高測量精度應(yīng)選用大尺寸的試樣、較小半徑和小熱容的熱線。本文所做工作可為瞬態(tài)熱線法熱物性測試技術(shù)的誤差估計(jì)提供基本的理論依據(jù)和參考。
[Abstract]:Transient hot wire method is a commonly used method for measuring thermal properties. It has been widely used in the measurement of thermal conductivity of powders, liquids, composite materials, wet porous media, and non-transparent and translucent solids at high temperature. In view of the characteristics of transient hot-wire method, error estimation is always a difficult problem in this kind of measurement technology. For this kind of technology, the error analysis of thermal conductivity measurement by numerical simulation is less common. In this paper, the measurement error of thermal conductivity of transient hot wire method is analyzed by numerical simulation, and the influence of various factors on the measurement error of thermal conductivity of transient hot wire method is analyzed. On the basis of describing the principle, model and classification of transient hot-wire method, the mathematical model is established, and the temperature field distribution and temperature value of monitoring point are obtained by numerical simulation with Fluent. According to the theoretical formula, the simulation value of thermal conductivity is obtained, and the measurement error of thermal conductivity is obtained by comparing the simulated value with the set value. According to the principle and hypothesis of transient hot wire method, different specimen size, hot wire radius and hot wire heat capacity are selected to simulate, and the relative error of thermal conductivity varies with different parameters. The results show that the temperature distribution obtained by numerical simulation is in agreement with the theoretical analysis. When other parameters are fixed, the measurement error increases with the decrease of sample size, with the increase of hot-wire radius, and with the increase of hot-wire heat capacity, and the transient hot-wire method is more suitable for measuring materials with small thermal conductivity. When the sample size w 脳 b 鈮，

本文編號：1895521