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  本文關(guān)鍵詞：密集顆粒物料流動(dòng)特性數(shù)值模擬研究　出處：《中國(guó)科學(xué)院大學(xué)(中國(guó)科學(xué)院過程工程研究所)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 密集顆粒物料 移動(dòng)床 離散元方法 計(jì)算流體力學(xué) 摩擦粘度模型

【摘要】：工業(yè)過程中常涉及到密集顆粒物料的處理,深入認(rèn)識(shí)密集顆粒物料的流動(dòng)特性對(duì)設(shè)計(jì)、優(yōu)化和放大相關(guān)設(shè)備至關(guān)重要。本文以移動(dòng)床和噴動(dòng)床為研究對(duì)象,考察系統(tǒng)中顆粒物料的流動(dòng)特性,探索現(xiàn)有密集顆粒物料相關(guān)本構(gòu)模型的預(yù)測(cè)精度與適用性。本論文第二章采用離散單元法模擬研究了移動(dòng)床中顆粒物料的卸料特性,為第三章連續(xù)性模擬結(jié)果的合理性提供驗(yàn)證數(shù)據(jù)。離散模擬結(jié)果表明,隨著初始堆積高度的增大,顆粒物料的流型逐漸由C類漏斗流過渡到B類半整體流。漏斗流結(jié)構(gòu)下,流動(dòng)區(qū)特征寬度隨卸料的進(jìn)行呈現(xiàn)(增大)—恒定—減小的變化趨勢(shì)。半整體流結(jié)構(gòu)下,當(dāng)床層高度降到某一臨界值時(shí),流型突變?yōu)槁┒妨?之后流動(dòng)區(qū)特征寬度呈單調(diào)遞減的變化趨勢(shì)。這一結(jié)果說明,移動(dòng)床卸料過程中,流動(dòng)區(qū)寬度與卸料歷史密切相關(guān)。第三章基于連續(xù)介質(zhì)模擬,考察了目前文獻(xiàn)中代表性的顆粒粘度模型(Schaeffer、S-S和μ(Ⅰ)模型)對(duì)模擬結(jié)果的影響。模擬結(jié)果表明,對(duì)于卸料初期為漏斗流的系統(tǒng),Schaeffer模型和μ(Ⅰ)模型都能預(yù)測(cè)出漏斗流流動(dòng)結(jié)構(gòu),但所預(yù)測(cè)的流動(dòng)區(qū)特征寬度的數(shù)值與變化趨勢(shì)明顯偏離離散單元法模擬結(jié)果;對(duì)于卸料初期為半整體流流型的系統(tǒng),Schaeffer模型和μ(Ⅰ)模型能夠預(yù)測(cè)出移動(dòng)床內(nèi)物料從B類半整體流向C類漏斗流的轉(zhuǎn)化過程,且流動(dòng)區(qū)特征寬度變化趨勢(shì)與離散單元法模擬結(jié)果定量一致。對(duì)于所考察的初始堆積高度,S-S模型的預(yù)測(cè)結(jié)果始終為半整體流,明顯偏離了離散單元法數(shù)值模擬的結(jié)果。第四章基于氣固噴動(dòng)床,進(jìn)一步檢驗(yàn)了以上三種粘度模型對(duì)模擬結(jié)果的影響。模擬結(jié)果表明,μ(Ⅰ)模型預(yù)測(cè)得到的噴泉區(qū)高度、平局空隙率以及噴動(dòng)區(qū)輪廓更接近于實(shí)驗(yàn)結(jié)果;Schaeffer模型得到的床層壓降最接近實(shí)驗(yàn)測(cè)量值。三種粘度模型在噴泉區(qū)與噴動(dòng)區(qū)內(nèi)的預(yù)測(cè)結(jié)果差異不大,但在環(huán)隙密相區(qū)內(nèi)μ(Ⅰ)模型的模擬結(jié)果明顯優(yōu)于其他模型。綜合考慮,相較于Schaeffer與S-S模型,μ(Ⅰ)模型在噴動(dòng)床預(yù)測(cè)中顯示出更大的優(yōu)越性。
[Abstract]:Industrial process often involves dealing with dense granular materials, the flow characteristics of dense granular materials for in-depth understanding of the design, optimization and scale-up of related equipment is very important. Based on the moving bed and spouted bed as the research object, the flow characteristics of granular material inspection system, to explore the forecasting precision and applicability of existing dense granular material constitutive correlation model. The second chapter of this paper studied material characteristics of unloading particles in the moving bed by discrete element method to provide validation data for the third chapter the rationality of continuous simulation results. The simulation results show that the discrete, with the initial accumulation height increases, particles flow gradually from the C class to the B class half funnel flow transition the whole flow funnel flow structure, flow characteristics of the width of unloading presented the trend of decrease (increase) - constant. Semi integral flow structure, when the height of bed down To a critical value, the flow pattern mutation funnel flow after flow region characteristic width monotonically decreasing. This result shows that the moving bed unloading process, flow zone width is closely related with the discharge history. The third chapter is based on the simulation of continuous medium, the effects of particle viscosity model at present in the literature on behalf of the (Schaeffer, S-S and (I) model) influence on the simulation results. The simulation results show that the system for early discharge funnel flow, Schaeffer model and mu (1) model can predict the flow structure of funnel flow, but the value and trend of flow characteristics predicted by the apparent width from the discrete element method simulation results; system for discharging the early semi integral flow, Schaeffer model and mu (I) model is able to predict the movement of materials in the bed from the B class to the C class of semi integral funnel flow transformation process, and the flow characteristics of wide area The degree of variation and discrete element method simulation results agree quantitatively. For the initial investigation of the pile height, the prediction result of S-S model is always half the overall flow, significantly deviated from the numerical simulation of discrete element method. The fourth chapter is based on the gas-solid spouted bed, to further test the effects of the above three kinds of viscosity model of simulation results simulation results show that u (I) models to predict the fountain height, draw air void and spout contour is more close to the experimental results; the pressure drop of the bed Schaeffer model can get the most close to the experimental values. Three viscosity model in the fountain area and spouted zone prediction results had little difference, but in the ring gap in the dense phase zone. (I) the simulation results of the model is better than the other models. Considering, compared with Schaeffer and S-S model, u (I) model in the spouted more advantages show bed prediction.

【學(xué)位授予單位】：中國(guó)科學(xué)院大學(xué)(中國(guó)科學(xué)院過程工程研究所)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TQ021.1

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