本文關(guān)鍵詞：同軸旋轉(zhuǎn)可壓縮氣體中液體射流及單液滴內(nèi)空化氣泡穩(wěn)定性研究　出處：《北京交通大學(xué)》2016年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 旋轉(zhuǎn) 可壓縮 空化氣泡 熱效應(yīng) 射流 液滴 穩(wěn)定性 色散方程

【摘要】：液體射流普遍存在于自然界和工程中；在柴油機(jī)、缸內(nèi)直噴汽油機(jī)以及燃?xì)廨啓C(jī)等動(dòng)力機(jī)械中,燃油的噴射、分裂霧化及其與空氣的混合是實(shí)現(xiàn)高效燃燒的基礎(chǔ)和前提,對發(fā)動(dòng)機(jī)的動(dòng)力性、經(jīng)濟(jì)性以及排放特性等具有重要的影響。燃油射流的分裂與霧化過程,實(shí)際上就是液體射流的失穩(wěn)過程；液體射流穩(wěn)定性問題一直以來都是內(nèi)燃機(jī)領(lǐng)域的一個(gè)研究熱點(diǎn)。論文采用理論解析和數(shù)值模擬方法對同軸旋轉(zhuǎn)可壓縮氣體中液體射流分裂與霧化問題進(jìn)行了研究；研究工作可以進(jìn)一步完善液體射流及分裂液滴內(nèi)空化氣泡穩(wěn)定性數(shù)學(xué)模型,加深對液體射流分裂與霧化機(jī)理的理解。建立了描述同軸旋轉(zhuǎn)可壓縮氣體中液體射流穩(wěn)定性的色散方程,并考慮了空化氣泡的影響；分別給出了時(shí)間模式和空間模式下色散方程的數(shù)值求解方法。在此基礎(chǔ)上,探討了射流周圍氣體的同軸旋轉(zhuǎn)以及射流及周圍氣體的可壓縮性對射流軸對稱擾動(dòng)和非軸對稱擾動(dòng)的作用以及對射流穩(wěn)定性的影響；對射流分裂液滴粒徑的計(jì)算公式進(jìn)行了改進(jìn)；研究了空化氣泡的存在所產(chǎn)生的射流物性變化對射流穩(wěn)定性的作用;對含空泡射流空間模式穩(wěn)定性與時(shí)間模式穩(wěn)定性的差異以及造成兩者之間差異的影響因素進(jìn)行了分析。通過研究,明確了射流周圍氣體同軸旋轉(zhuǎn)、射流及周圍氣體可壓縮性以及空化氣泡對射流穩(wěn)定性的作用,含空泡射流空間模式穩(wěn)定性與時(shí)間模式穩(wěn)定性的差異及其影響因素。給出了存在熱效應(yīng)的液體射流自由表面三維擾動(dòng)控制方程,得到了擾動(dòng)壓力方程、速度方程和溫度方程,建立了描述同軸旋轉(zhuǎn)可壓縮氣體中液體射流熱穩(wěn)定性的色散方程,并對色散方程及其求解方法進(jìn)行了驗(yàn)證。在此基礎(chǔ)上,進(jìn)行了存在熱效應(yīng)的同軸旋轉(zhuǎn)可壓縮氣體中液體射流穩(wěn)定性分析。通過研究,明確了射流內(nèi)部溫度梯度對液體射流表面擾動(dòng)波發(fā)展的影響,液體射流表面與周圍氣體間溫差對液體射流穩(wěn)定性的作用。基于非線性穩(wěn)定性理論,推導(dǎo)出描述液體射流表面擾動(dòng)的一階與二階擾動(dòng)控制方程,對擾動(dòng)控制方程進(jìn)行了解析求解,確定了氣液交界面一階與二階邊界條件；建立了描述同軸旋轉(zhuǎn)可壓縮氣體中含空泡液體射流非線性穩(wěn)定性的色散方程,并對色散方程進(jìn)行了驗(yàn)證分析。在此基礎(chǔ)上,進(jìn)行了射流表面一階與二階擾動(dòng)及其發(fā)展的分析,對線性與非線性穩(wěn)定性理論下的射流形態(tài)與分裂進(jìn)行了比較,進(jìn)行了同軸旋轉(zhuǎn)可壓縮氣體中含空泡液體射流非線性穩(wěn)定性研究。通過研究,明確了射流表面擾動(dòng)的發(fā)展?fàn)顟B(tài),線性與非線性穩(wěn)定性理論下液體射流的形態(tài)及分裂特點(diǎn),以及射流周圍氣體的同軸旋轉(zhuǎn)、射流和周圍氣體的可壓縮性以及空化氣泡對射流形態(tài)及射流分裂長度的影響。在同時(shí)考慮空化氣泡、分裂液滴及空氣粘性的條件下,建立了描述燃油分裂液滴內(nèi)空化氣泡穩(wěn)定性的色散方程,對色散方程進(jìn)行了驗(yàn)證分析,并對色散方程的根進(jìn)行了討論。在此基礎(chǔ)上,從空泡受力角度對空泡的穩(wěn)定性及其影響因素進(jìn)行了研究,建立了分裂液滴內(nèi)空泡臨界破碎準(zhǔn)則,并應(yīng)用該準(zhǔn)則對分裂液滴內(nèi)空泡的破碎特性及影響因素進(jìn)行了分析。通過研究,明確了空化氣泡、分裂液滴及空氣的粘性對空泡穩(wěn)定性的影響,空泡慣性力、空泡可壓縮性力、液滴內(nèi)外部氣動(dòng)力以及空泡液滴界面處表面張力對空泡穩(wěn)定性的作用,以及分裂液滴內(nèi)空泡的破碎特性及影響因素�；赩OF方法建立了描述液滴內(nèi)空化氣泡生長及潰滅的計(jì)算模型,并對數(shù)值模擬結(jié)果進(jìn)行了驗(yàn)證分析。在此基礎(chǔ)上,通過數(shù)值模擬研究,探討了液滴內(nèi)空泡生長的控制機(jī)理,分析了液滴內(nèi)空泡生長的影響因素,研究了液滴內(nèi)空泡潰滅過程及其特征參數(shù)的變化規(guī)律；在考慮相變的條件下,對空泡潰滅計(jì)算模型進(jìn)行了改進(jìn),并在此基礎(chǔ)上對存在相變的液滴內(nèi)空泡的潰滅歷程進(jìn)行了分析。通過研究,揭示了液滴內(nèi)空泡生長的控制機(jī)理,明確了表面張力系數(shù)、液滴粘度和液滴密度對空泡生長過程的影響,空泡潰滅過程中潰滅壓力、潰滅體積、反彈壓力及反彈體積的變化規(guī)律,以及存在相變時(shí)液滴內(nèi)空泡的潰滅歷程。
[Abstract]:Liquid jet exists widely in nature and engineering; in diesel engine, Disi engine and gas turbine power machinery, fuel injection, atomization and mixing of air is the basis and prerequisite for achieving efficient combustion, the engine power, has an important effect on economy and emission characteristics. The breakup and atomization of the fuel jet, is actually a liquid jet instability process; liquid jet stability problem has been a hot research topic in the field of internal combustion engines. The simulation of the coaxial rotation of breakup and atomization of liquid jet in compressed gases are studied by theoretical analysis and numerical research work can be further used in this paper; improvement of liquid jet and droplet fission in the cavitation bubble stability mathematical model, deepen our understanding of the mechanisms of breakup and atomization of liquid was established to describe the understanding. The dispersion equation of coaxial rotation can stability liquid jet of compressed gas, and the influence of the cavitation bubble; the numerical method for solving the dispersion equation of time and space mode mode are given. Based on this, discusses the surrounding gas jet jet and coaxial rotating and surrounding gas compressibility of axisymmetric jet disturbance and the non axisymmetric disturbances and the influence on the stability of jet; jet droplet size formula has been improved; the jet property change of cavitation bubble produced by the presence of jet stability; influence factors of the difference between the two of physaliferous jet space mode and time stability the difference of stability and mode are analyzed. Through the research, the surrounding gas jet coaxial rotation, jet and the surrounding gas compressibility and air Effect of bubbles on the jet stability, factors of physaliferous jet space mode stability and time stability mode and its influence is given. The control equation of liquid free surface jet 3D disturbance of thermal effect, pressure perturbation equation, velocity equation and temperature equation was established to describe the coaxial rotation dispersion equation of liquid jet thermal stability can be compressed gas, and the dispersion equation and its solving method are verified. Based on this, the stability analysis of liquid jet of compressed gas in rotating coaxial can exist thermal effect were carried out. Through the research, the temperature gradient inside the jet disturbance wave development on the liquid jet surface clear, effect of liquid jet surface and surrounding gas the temperature difference on the liquid jet stability. Nonlinear stability theory based on the first and two description of the liquid jet surface disturbance is derived The control equation of order disturbance, the disturbance control equation is solved analytically, the gas-liquid interface of first order and two order boundary conditions; to describe the coaxial rotation can be dispersion equation with nonlinear stability of cavitation of liquid jet of compressed gas, and the dispersion equation is verified and analyzed. On this basis, the analysis of jet the surface of the one and two order perturbation and the development of the jet shape and splitting of the theory of linear and nonlinear stability were compared, can study on nonlinear stability of coaxial rotating liquid jet cavity containing a compressed gas was carried out. Through the research, clarify the development condition of jet surface disturbance, the morphology and characteristics of the theory of linear split liquid jet with the nonlinear stability, and coaxial jet gas around the rotating jet and the surrounding gas compressibility and cavitation bubbles on the jet morphology and shoot The effect of flow split length. Considering the cavitation bubbles, splitting droplet and viscosity of air conditions, the dispersion equation is established to describe the fuel droplet fission in cavitation bubble stability, the dispersion equation is verified, and the roots of the dispersion equation are discussed. On this basis, the force from the bubble the angle of stability of cavity and its influencing factors were studied. A droplet fission cavity in the critical fracture criterion, crushing factor characteristic and the influence and the application of the criterion of cavitation split within the droplets are analyzed. Through the research, the cavitation bubbles, splitting droplet and air viscosity on bubble stability. Cavitation bubble inertia force, compression force, droplet internal and external aerodynamic and bubble droplet surface tension effect on bubble stability, and crushing characteristics and the impact of droplets within the cavity due to split . calculation model to describe the droplets within the cavitation bubble growth and collapse is established based on the VOF method, and the numerical simulation results are verified and analyzed. On this basis, through numerical simulation, discusses the control mechanism of droplet vacuoles in growth, analyzes the factors influence of droplet vacuoles, variation study on the features and parameters of the liquid droplet in the process of bubble collapse; in considering the transformation conditions, the bubble collapse calculation model is improved, and on the basis of the analysis of the collapse process exist within the bubble droplet phase. Through the research, the control mechanism of droplet vacuoles in growth reveals clear the influence of surface tension coefficient, droplet viscosity and droplet density on the growth process of the bubble, the collapse pressure during the bubble collapse collapse volume variation and rebound rebound pressure volume, and in liquid phase The collapse process drop vacuoles within.

【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：TK401
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本文編號(hào)：1430794