本文關(guān)鍵詞： 多孔介質(zhì) 自然對流 傳熱實驗 應(yīng)用基礎(chǔ)　出處：《遼寧工程技術(shù)大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：開展多孔介質(zhì)內(nèi)對流與傳熱的基礎(chǔ)與應(yīng)用研究,有利于建筑節(jié)能新技術(shù)的發(fā)展,是解決基礎(chǔ)科學(xué)問題的需要。本文采用理論分析和實驗研究的方法研究多孔介質(zhì)內(nèi)的傳熱問題,利用數(shù)值計算的方法研究流體瑞利數(shù)、達西數(shù)、模型高寬比對多孔介質(zhì)流動與傳熱的影響,主要結(jié)論如下：首先,以理論為指導(dǎo)的實驗研究結(jié)果表明：多孔介質(zhì)內(nèi)部的非穩(wěn)態(tài)傳熱過程大致分為三個階段,即受初始溫度分布影響階段、溫度升高階段、新的熱平衡階段；前兩個階段中,上部溫度場最先受到邊界影響,下部受到邊界影響時間比較遲；溫差越大,溫度場越容易受到邊界條件影響,初始溫度影響的時間就越短；在第三個階段,溫度場中呈現(xiàn)明顯的分層現(xiàn)象,上部溫度高,下部溫度低,這是由于多孔介質(zhì)內(nèi)部出現(xiàn)自然對流造成的結(jié)果。其次,將數(shù)值計算的結(jié)果與實驗測定結(jié)果相比較發(fā)現(xiàn)：在新的熱平衡狀態(tài)下,數(shù)值計算結(jié)果與實驗測定結(jié)果最大相對誤差達到10.98%,驗證了數(shù)值計算方法和參數(shù)設(shè)置的正確性。數(shù)值計算結(jié)果表明：流體瑞利數(shù)較小(Ra105)時,傳熱以導(dǎo)熱為主,增大瑞利數(shù),對流作用就占主導(dǎo)作用；達西數(shù)Da10-6時,增大達西數(shù),流體流動變得越容易,對流作用就越強；模型高寬比為1時,努塞爾數(shù)Nu最大,傳熱效率最高；在線性高溫條件下,中間位置以下部分,Nu為正值且隨高度增加而減小,熱量由高溫壁面向腔內(nèi)傳熱；中間位置以上部分,Nu為負值且隨高度增加而減小,熱量由腔內(nèi)向高溫壁面?zhèn)鳠幔坏撞考訜釙r,增大瑞利數(shù),系統(tǒng)穩(wěn)定性被破壞,出現(xiàn)分叉現(xiàn)象。
[Abstract]:The basic and applied research on convection and heat transfer in porous media is beneficial to the development of new building energy saving technology and is the need to solve the basic scientific problems. In this paper, theoretical analysis and experimental study are used to study the heat transfer problem in porous media. The effects of Rayleigh number, Darcy number and aspect ratio of the model on the flow and heat transfer in porous media are studied by numerical method. The main conclusions are as follows: first, The experimental results under the guidance of theory show that the unsteady heat transfer process in porous media can be divided into three stages, namely, the stage affected by initial temperature distribution, the stage of temperature rise, the stage of new heat balance, the first two stages, The upper temperature field is first affected by the boundary, and the lower part is affected by the boundary. The larger the temperature difference is, the more vulnerable the temperature field is to the boundary condition, and the shorter the initial temperature effect is; in the third stage, There are obvious stratification phenomena in the temperature field, the upper temperature is high and the lower part is low, which is caused by the natural convection in the porous media. Secondly, By comparing the numerical results with the experimental results, it is found that in the new thermal equilibrium state, The maximum relative error between the numerical results and the experimental results is 10.98, which verifies the correctness of the numerical calculation method and the parameter setting. The numerical results show that the heat transfer is mainly heat conduction and increases the Rayleigh number when the Rayleigh number of fluid is smaller than that of Ra105). When the Darcy number is increased, the flow of the fluid becomes easier and the convection effect becomes stronger, the ratio of height to width is 1:00, the Nu number is the largest and the heat transfer efficiency is the highest. The lower part of the middle position is positive and decreases with the increase of height, and the heat is heat transfer from the high temperature wall to the cavity; the upper part of the middle position is negative and decreases with the increase of height, and the heat is heat transfer from the cavity to the high temperature wall; when the bottom is heated, When the Rayleigh number is increased, the stability of the system is destroyed and the bifurcation occurs.
【學(xué)位授予單位】：遼寧工程技術(shù)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TU111

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