發(fā)布時間：2018-05-12 12:02

  本文選題：噴動床 + 顆粒動理學理論�。� 參考：《西北大學》2017年碩士論文

【摘要】：噴動床內(nèi)部極有規(guī)律的氣固流動特性,使得其在農(nóng)業(yè)、化工等很多領(lǐng)域都有廣泛的應(yīng)用。自上世紀五十年代起,噴動床內(nèi)部流動機理的研究與探索一直是研究者們關(guān)注的熱點與核心問題,從實驗尺度到工業(yè)應(yīng)用尺度的放大更是困擾工程界和學術(shù)界的難點課題。由于噴動床氣固流場受控因素的復雜性,以及受實驗條件和測量手段的限制,使得探討和認識其內(nèi)部流動與放大的本質(zhì)機理變得異常艱難。隨著計算流體力學的出現(xiàn)、數(shù)值計算算法的逐步完善以及計算機硬件的不斷更新,使得數(shù)值模擬逐漸成為了研究噴動床的重要手段之一。本文基于計算流體力學的方法,在歐拉-歐拉雙流體框架下結(jié)合顆粒動理學理論對不同維度的矩形倒椎體噴動床進行數(shù)值研究。模擬中將氣-固兩相均當做連續(xù)相處理,采用相同的質(zhì)量、動量守恒方程。為了節(jié)約計算資源均采用軸(面)對稱網(wǎng)格進行模擬。主要研究內(nèi)容包括以下三部分:第一部分:對Liu[28]等人準二維噴動床實驗采用五種曳力模型和四種徑向分布函數(shù)模型進行模擬,得到了不同工況下顆粒體積分數(shù)云圖、顆粒軸向速度軸向分布和徑向分布。通過與實驗值進行對比,探索出描述該體系中氣固兩相動量交換的最佳曳力模型和描述顆粒徑向分布概率的徑向分布函數(shù)。第二部分:采用第一部分的研究結(jié)果作為基礎(chǔ)的邊界條件,針對厚度為Omm(二維)、15mm(準二維)和100mm(三維)三個維度的矩形噴動床,通過顆粒壁面滑移系數(shù)和碰撞恢復系數(shù)作為模型參數(shù),探討顆粒與壁面之間由于摩擦和碰撞而產(chǎn)生的動量交換,探索碰撞和摩擦等微觀動力學事件影響宏觀流場的規(guī)律。通過實驗對比獲得最優(yōu)參數(shù)值。第三部分:采用第一部分和第二部分得出的最優(yōu)邊界條件,以增加噴動床厚度的方式(厚度:Omm、15mm、30mm、50mm、75mm和100mm)不斷的放大矩形噴動床,分別探討表觀氣速、顆粒與壁面滑移系數(shù)和碰撞恢復系數(shù)在放大過程中影響宏觀流場的規(guī)律。
[Abstract]:Spouted bed has been widely used in many fields such as agriculture and chemical industry due to its regular gas-solid flow characteristics. Since the 1950s, the study and exploration of the flow mechanism in spouted bed has been the focus and core problem of researchers. From the scale of experiment to the scale of industrial application, the enlargement of scale has been a difficult problem in engineering and academic circles. Due to the complexity of controlled factors of gas-solid flow field in spouted bed and the limitation of experimental conditions and measurement methods, it is very difficult to study and understand the essential mechanism of internal flow and amplification of spouted bed. With the emergence of computational fluid dynamics (CFD), the gradual improvement of numerical algorithms and the continuous updating of computer hardware, numerical simulation has gradually become one of the important means to study spouted bed. Based on the computational fluid dynamics (CFD) method, a numerical study on spouted bed of rectangular inverted vertebrae with different dimensions is carried out under the framework of Euler-Euler dual fluid and particle kinetic theory. The gas-solid phase is treated as continuous phase with the same mass and momentum conservation equation. In order to save computing resources, the axisymmetric mesh is used to simulate. The main research contents are as follows: in the first part, five drag models and four radial distribution function models are used to simulate the quasi-two-dimensional spouted bed experiment of Liu [28], and the cloud diagram of particle volume fraction under different working conditions is obtained. Axial and radial distribution of particle velocity. By comparing with the experimental data, the optimal drag model and radial distribution function describing the probability of particle radial distribution in the system are explored. The second part: using the results of the first part as the boundary condition, the rectangular spouted bed with three dimensions of Omm (2-D) 15mm (quasi-2-D) and 100mm (3D) is applied to the spouted bed with the thickness of Omm (2-D) 15mm (quasi-2-D) and 100mm (3D). The slip coefficient and recovery coefficient of particle wall are used as model parameters to study the momentum exchange between particles and wall due to friction and collision, and to explore the law of impact of micro dynamic events such as collision and friction on macroscopic flow field. The optimal parameter values are obtained by experimental comparison. The third part: by using the optimal boundary conditions obtained in the first and second parts, the rectangular spouted bed is continuously enlarged in the way of increasing the thickness of spouted bed (the thickness of the spouted bed is: 1: Omm1 15mm / 30mm / 50mm / 75mm and 100mm), and the apparent gas velocities are discussed respectively. The slip coefficient of particle and wall and the coefficient of collision recovery affect the law of macroscopic flow field in the process of amplification.
【學位授予單位】：西北大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TQ021.1

【參考文獻】

相關(guān)期刊論文 前7條

1 Chanchal Loha;Himadri Chattopadhyay;Pradip K.Chatterjee;;Effect of coefficient of restitution in Euler-Euler CFD simulation of fluidized-bed hydrodynamics[J];Particuology;2014年04期

2 張彩虹;黃立新;謝普軍;游鳳;張耀雷;;不同氣速下噴動床噴泉區(qū)顆粒特性的模擬分析[J];化工進展;2013年04期

3 朱衛(wèi)兵;朱潤孺;邢力超;孫巧群;;噴動床DEM模擬曳力模型評價[J];哈爾濱工程大學學報;2011年05期

4 Salar Azizi;Seyyed Hossein Hosseini;M.Moraveji;Goodarz Ahmadi;;CFD modeling of a spouted bed with a porous draft tube[J];Particuology;2010年05期

5 黃衛(wèi)星;諸海碧;黎梅;李海龍;祝京旭;;氣固循環(huán)床上行兩相流顆粒曳力系數(shù)研究[J];四川大學學報(工程科學版);2008年02期

6 ;DISCRETE PARTICLE SIMULATION OF SIZE SEGREGATION OF PARTICLE MIXTURES IN A GAS FLUIDIZED BED[J];China Particuology Science and Technology of Particles;2006年Z1期

7 李水清,姚強,趙香龍,鄭義忠;噴動床內(nèi)顆粒濃度的實驗測量和理論模擬[J];工程熱物理學報;2005年05期

相關(guān)碩士學位論文 前1條

1 麥錫源;核燃料包覆噴動床氣固流動特性模擬研究[D];中國科學院研究生院（上海應(yīng)用物理研究所）;2015年

，

本文編號：1878540