發(fā)布時間：2018-06-18 17:19

  本文選題：火災(zāi) + 一維湍流模型��； 參考：《中國科學(xué)技術(shù)大學(xué)》2013年博士論文

【摘要】：實際火災(zāi)是湍流燃燒過程,而在湍流燃燒中湍流流動與復(fù)雜化學(xué)是時空多尺度耦合作用的。研究湍流與復(fù)雜化學(xué)的相互作用是一項既有挑戰(zhàn)也十分有意義的課題。湍流的空間尺度可以分為含能尺度、慣性子區(qū)尺度和耗散尺度三個層次。湍流渦旋從最小的耗散尺度開始就與火焰有著強烈的相互作用。 數(shù)值模擬研究湍流與復(fù)雜化學(xué)的相互作用需要解決耦合詳細化學(xué)反應(yīng)機理的耗散尺度湍流反應(yīng)流模擬,和海量模擬結(jié)果診斷分析的兩個難題。本文采用一維湍流模型(one-dimensional turbulence, ODT)和化學(xué)反應(yīng)爆炸模式分析方法(chemical explosive mode analysis, CEMA)解決了這兩個難題,建立了ODT+CEMA分析湍流與復(fù)雜化學(xué)相互作用的數(shù)值分析平臺,并對典型滅火劑與氫氣射流火焰的相互作用進行了數(shù)值模擬和深入分析。 復(fù)雜化學(xué)研究中,詳細化學(xué)反應(yīng)機理的分析及簡化對實現(xiàn)湍流耦合復(fù)雜化學(xué)的數(shù)值模擬十分重要。本文中采用關(guān)系圖法對典型碳氫燃料反應(yīng)機理進行了簡化研究。不但研究了在保持一定計算精度情況下簡化機理能達到的最小規(guī)模,還深入分析了方法參數(shù)對簡化結(jié)果的影響,并且引入強關(guān)系組分群的概念,分析了復(fù)雜化學(xué)反應(yīng)機理中強關(guān)系組分群的聚集、分布情況。為了加快反應(yīng)機理的計算,本文還做了利用圖形顯卡并行計算求解大型化學(xué)反應(yīng)機理的研究,在大型機理情況下計算加速效果明顯。 一維湍流模型ODT,可以實現(xiàn)耦合復(fù)雜化學(xué)的耗散尺度湍流反應(yīng)流模擬。本文介紹了ODT模型的計算框架、湍流模擬機制和數(shù)值求解方法。并用此方法模擬分析了氫氣射流火焰,以及添加典型滅火劑后的射流火焰基本特性。 高精度的湍流反應(yīng)流模擬會產(chǎn)生海量的計算數(shù)據(jù),傳統(tǒng)采用典型系統(tǒng)參數(shù)如溫度、關(guān)鍵組分的濃度,甚至一階導(dǎo)數(shù)的分析方法已經(jīng)不適合處理如此龐大、精細的計算結(jié)果�；瘜W(xué)反應(yīng)爆炸模式分析方法是一種分析湍流反應(yīng)流局部系統(tǒng)特征值的方法。本文系統(tǒng)介紹了化學(xué)反應(yīng)爆炸模式分析方法的數(shù)學(xué)基礎(chǔ)和基于ODT模擬數(shù)據(jù)的湍流反應(yīng)流信息分析方法。 通過對添加滅火劑的氫氣空氣預(yù)混熱自燃模型的化學(xué)反應(yīng)爆炸模式分析發(fā)現(xiàn),系統(tǒng)反應(yīng)進行最劇烈的時候也是最大正特征值發(fā)生明顯變化的時刻。添加了滅火劑后,熱自燃時間不但明顯推遲,其反應(yīng)進程和最大正特征值的突變性更加明顯�；瘜W(xué)反應(yīng)爆炸模式分析可以直觀的觀察到湍流反應(yīng)流局部系統(tǒng)狀態(tài)的變化,對診斷湍流火焰中的熱自燃、熄火、重燃等行為十分有效。 局部Damkohler數(shù)是控制火焰結(jié)構(gòu),研究湍流與復(fù)雜化學(xué)相互作用的重要參數(shù)。在本文分析中重新定義了Damkohler數(shù)。通過分析湍流火焰在新Da數(shù)空間的散點分布發(fā)現(xiàn)：新定義的Da數(shù)是判定局部熄火的良好標準,而滅火劑的作用途徑主要是通過增大局部反應(yīng)系統(tǒng)的熱自燃時間,進而減小Da數(shù),增加熄火概率。 通過分析,本文還解釋了Re數(shù)增加時滅火劑滅火效果增加的原因。研究結(jié)果明確指出了主要組分和主要基元反應(yīng)在射流火焰中的作用區(qū)域,以及在火焰抑制效果不同時,火焰中心區(qū)域主要作用組分和基元反應(yīng)的差異。 本文的主要創(chuàng)新點和貢獻在于：為研究湍流與復(fù)雜化學(xué)相互作用,建立了ODT+CEMA的數(shù)值分析平臺,提供了一種分析湍流與復(fù)雜化學(xué)相互作用的新方法。
[Abstract]:The actual fire is a turbulent combustion process, and the turbulent flow and the complex chemistry are multiscale coupling in turbulent combustion. The study of the interaction between turbulence and complex chemistry is a challenging and meaningful subject. The spatial scale of turbulence can be divided into three levels, including the energy scale, the inertial sub region scale and the dissipative scale. The turbulent vortex has a strong interaction with the flame from the minimum dissipation scale.
The numerical simulation of the interaction between turbulence and complex chemistry needs to solve the dissipative scale turbulent reaction flow simulation of the coupled detailed chemical reaction mechanism and the two difficult problems in the diagnosis and analysis of the mass simulation results. This paper uses the one-dimensional turbulence model (one-dimensional turbulence, ODT) and the chemical reaction explosion model analysis method (chemical explo). Sive mode analysis, CEMA) solved these two problems and established a numerical analysis platform for the analysis of the interaction between turbulence and complex chemistry by ODT+CEMA. The interaction between the typical fire extinguishing agent and the hydrogen jet flame was numerically simulated and analyzed.
In the complex chemical study, the analysis and simplification of the detailed chemical reaction mechanism are very important for the realization of the numerical simulation of the turbulent coupled complex chemistry. In this paper, the relationship diagram method is used to simplify the study of the reaction mechanism of typical hydrocarbon fuels. The influence of the method parameters on the simplified results is deeply analyzed, and the concept of strong relation group group is introduced, and the aggregation and distribution of the strong relation group in the complex chemical reaction mechanism are analyzed. In order to accelerate the calculation of the reaction mechanism, this paper also makes a study of the large chemical reaction mechanism by using the graphic graphics card parallel calculation, in large scale. In the case of mechanism, the acceleration effect is obvious.
A one-dimensional turbulent model ODT can be used to simulate the dissipative scale turbulent reaction flow in coupled complex chemistry. This paper introduces the calculation framework of the ODT model, the mechanism of turbulence simulation and the numerical solution method, and uses this method to simulate and analyze the hydrogen jet flame and the basic characteristics of the jet flame after the addition of typical fire extinguishing agents.
The high precision simulation of turbulent reaction flow will produce massive computational data. Traditional analysis methods of typical system parameters such as temperature, concentration of key components and even first derivative are not suitable to deal with such huge and fine calculation results. The analysis method of chemical reaction explosion mode is a kind of analysis of local system characteristics of turbulent reaction flow. The mathematical basis of chemical reaction explosion mode analysis method and the information analysis method of turbulent reaction flow based on ODT simulation data are systematically introduced in this paper.
Through the analysis of the chemical reaction explosion mode of the premixed combustion model of hydrogen air premixed with fire extinguishing agent, it is found that the most intense time is also the time when the maximum positive eigenvalue changes obviously. After adding the fire extinguishing agent, the time of thermal spontaneous combustion not only postpones obviously, but its reaction process and the maximum positive eigenvalue have more abrupt mutagenicity. It is obvious that the analysis of chemical reaction explosion mode can be used to observe the changes of the local system state of the turbulent reaction flow, and it is very effective for the diagnosis of thermal spontaneous combustion, extinguishing and reignition in the turbulent flame.
The local Damkohler number is an important parameter for controlling the flame structure and studying the interaction between turbulence and complex chemistry. In this paper, the number of Damkohler is redefined. By analyzing the scattered point distribution of the turbulent flame in the new Da number space, it is found that the newly defined number of Da is a good criterion for the determination of the local quenching, and the main way of the action of the fire extinguishing agent is to pass through the fire extinguishing agent. The thermal self ignition time of the local reaction system is increased, thus reducing the Da number and increasing the probability of extinction.
Through analysis, the reasons for increasing the fire extinguishing effect of the fire extinguishing agent when the Re number is increased are explained. The results clearly point out the main component and the main element reaction in the efflux flame, and the difference in the main component and the basic element reaction in the flame center area when the effect of the flame suppression is different.
The main innovations and contributions of this paper are: To study the interaction between turbulence and complex chemistry, a numerical analysis platform for ODT+CEMA is set up, and a new method for analyzing the interaction of turbulence and complex chemistry is provided.
【學(xué)位授予單位】：中國科學(xué)技術(shù)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2013
【分類號】：O643.21;TU998.1

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