本文選題：低溫 + 相變��； 參考：《東南大學(xué)》2015年碩士論文

【摘要】：隨著低溫技術(shù)的發(fā)展,諸如液氫、液氧等低溫液體越來越得到普及,特別作為低溫推進劑在液體火箭中得到應(yīng)用,所以低溫液體的制取以及貯存方面的安全問題也越來越得到重視。貯存安全問題主要研究的是低溫相變問題,而和常溫相變問題不同,對于低溫相變問題因為低溫氣液分子之間的相互作用力更加會影響到相變發(fā)生,所以低溫液體的貯存相變方面的研究必然要深入到微觀機理方面,所以本文利用基于微觀的格子Boltzmann方法(Lattice Boltzmann Method簡稱LBM)中粒子與粒子之間的相互作用力來促使氣液相變和相分離來研究低溫相變問題。本文首先闡述了LBM演化方程、邊界條件設(shè)置、兩相流模型及編程思路。然后基于LBM多相模型利用Fortran編制程序模擬出液滴的聚集,證明了LBM相界面的存在。利用相界面結(jié)合相變模型發(fā)展了LBM多相模型,模擬出低溫液滴的蒸發(fā)過程,分析在低溫環(huán)境下不同的過熱度下,液滴的蒸發(fā)速率會隨著過熱度變大而變快。在給定了具有重力的實際過程中,模擬出液滴在垂直管道中不斷進行氣液相變的現(xiàn)象,初步將格子Boltzmann理論應(yīng)用于低溫液體復(fù)雜相變領(lǐng)域。本文最后將LBM與實際的低溫流體進行相結(jié)合分析,利用Fortran編制程序,基于引入狀態(tài)方程的參數(shù)可調(diào)整型單組分相變模型,將PT狀態(tài)方程引入該模型發(fā)展了單組分多相模型并進行了驗證,通過模型成功對氮、氫、氧、氦,這四種典型的低溫實際流體進行模擬研究,將模擬結(jié)果與Maxwell理論解進行比較分析,得出基于PT狀態(tài)方程的模型最優(yōu)值。在最優(yōu)值的基礎(chǔ)上,將液滴和氣泡置于計算區(qū)域中,分析得出界面密度梯度與溫度之間成反比關(guān)系。LBM多相模型第一次應(yīng)用到實際的低溫流體工質(zhì)中,同時利用作用力模型解決了理論解與模擬值的偏差問題,具有非常重要的工程意義,也為揭示低溫工程相變現(xiàn)象的機理奠定了LBM理論基礎(chǔ)。
[Abstract]:With the development of cryogenic technology, cryogenic liquids such as liquid hydrogen and liquid oxygen are becoming more and more popular, especially used as cryogenic propellants in liquid rockets. Therefore, more and more attention has been paid to the production and storage of cryogenic liquids. Storage safety is mainly concerned with phase transition at low temperature, but different from phase transition at room temperature, phase transition at low temperature is more affected by interaction between gas and liquid molecules at low temperature. Therefore, the research on the storage phase transition of cryogenic liquids must go deep into the microscopic mechanism. Therefore, the interaction between particles and particles in lattice Boltzmann Method based on microcosmic lattice Boltzmann method is used to promote the gas-liquid phase transition and phase separation to study the phase transition at low temperature. In this paper, the evolution equation of LBM, the setting of boundary conditions, the model of two-phase flow and the programming idea are introduced. Then the aggregation of droplets is simulated by using Fortran program based on LBM multiphase model, which proves the existence of LBM phase interface. The LBM multiphase model is developed by using the phase interface and phase transformation model, and the evaporation process of the droplet at low temperature is simulated. It is analyzed that the evaporation rate of the droplet will become faster with the increase of the superheat at different superheat degrees in the low temperature environment. In the given actual process with gravity, the phenomenon of continuous gas-liquid phase transition of droplets in vertical pipes is simulated, and the lattice Boltzmann theory is applied to the complex phase transition field of cryogenic liquids. In the end, the LBM is combined with the actual low-temperature fluid, and the program is compiled by Fortran, based on the parameter adjustable one-component phase transition model with the introduction of the equation of state. The PT equation of state was introduced into the model to develop and verify the multiphase model. The simulation of nitrogen, hydrogen, oxygen, helium and four typical low-temperature real fluids was carried out. The simulation results are compared with the Maxwell theoretical solution and the optimal value of the model based on PT equation of state is obtained. On the basis of the optimum value, the droplets and bubbles are placed in the calculation area, and the inverse relationship between the interface density gradient and the temperature is obtained. The LBM multiphase model is applied to the practical low-temperature fluid for the first time. At the same time, the problem of deviation between the theoretical solution and the simulated value is solved by using the force model, which has very important engineering significance and lays the LBM theoretical foundation for revealing the mechanism of phase transition in low temperature engineering.
【學(xué)位授予單位】：東南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：V511.6

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