本文關(guān)鍵詞： 多相流 VOF模型 DPM離散相模型 PM2.5/PM10 氣泡　出處：《西南交通大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著經(jīng)濟(jì)快速發(fā)展,世界各地的霧霾現(xiàn)象日益嚴(yán)重。霧霾中的PM2.5/PM10微顆粒對(duì)人體健康有著嚴(yán)重的危害性,因此對(duì)空氣中PM2.5/PM10顆粒的濃度進(jìn)行檢測(cè)是非常有必要的。針對(duì)霧霾現(xiàn)象,本論文提出了一種基于石英晶體微天平和介電泳(Dielectrophoresis,DEP)原理的PM2.5/PM10濃度監(jiān)測(cè)系統(tǒng)。為了提高PM2.5/PM10濃度監(jiān)測(cè)系統(tǒng)的監(jiān)測(cè)精度以及實(shí)現(xiàn)系統(tǒng)對(duì)PM2.5/PM10兩種顆粒濃度分別監(jiān)測(cè),本論文采用離散相方法(Discrete Phase Model,DPM)與流體體積方法(Volume of Fluid,VOF)相耦合的方式對(duì)監(jiān)測(cè)系統(tǒng)中PM2.5/PM10微顆粒的運(yùn)動(dòng)特性進(jìn)行了數(shù)值模擬。為了便于描述微顆粒運(yùn)動(dòng)特性,本文將顆粒運(yùn)動(dòng)最接近檢測(cè)池底部的位置稱為顆粒的"沉降點(diǎn)"位置。在固-液兩相流模型的微顆粒運(yùn)動(dòng)軌跡模擬中,分別研究了液體粘度、液體密度、入口速度因素對(duì)微顆粒運(yùn)動(dòng)軌跡的影響,結(jié)果表明:液體粘度由0.01Pa·s減小到1×10-Pa·s過程中,顆粒"沉降點(diǎn)"位置隨著液體粘度的減小而下降,當(dāng)液體粘度從1×10~(-4)Pa·s繼續(xù)減小到1×10~(-6)Pa·s時(shí),顆粒"沉降點(diǎn)"位置隨著液體粘度的減小而略微上升;在液體密度從500kg/m~3增加到2500kg/m~3過程中,顆粒"沉降點(diǎn)"位置隨著液體密度的減小而略微下降;入口速度由0.2m/s增加到10m/s的過程中,不同直徑顆粒的運(yùn)動(dòng)軌跡分離程度變大且"沉降點(diǎn)"位置有所上升。在固-液兩相流的基礎(chǔ)上,利用VOF+DPM耦合模型模擬研究了氣-液-固三相流中入口速度、液體粘度、液體密度、氣液兩相表面張力這些因素對(duì)微顆粒軌跡的影響,結(jié)果發(fā)現(xiàn):入口速度由0.2m/s增大到2m/s過程中,不同直徑微顆粒的運(yùn)動(dòng)軌跡分離程度不斷增加,其中PM2.5顆粒"沉降點(diǎn)"位置隨著入口速度增加而上升,PM10顆粒"沉降點(diǎn)"位置隨著入口速度增加先降低隨后上升;液體粘度從0.001Pa·s減小到1×10~(-6)Pa·s過程中,微顆粒"沉降點(diǎn)"位置不斷下降;當(dāng)液體密度500kg/m~3增大到2000kg/m~3過程中,顆粒的"沉降點(diǎn)"位置出現(xiàn)先下降后上升的趨勢(shì),在1500kg/m~3時(shí),顆粒"沉降點(diǎn)"具有一個(gè)最低位置;氣液兩相表面張力的變化也對(duì)微顆粒的運(yùn)動(dòng)產(chǎn)生規(guī)律性影響,當(dāng)表面張力為0.065N/m時(shí),顆粒"沉降點(diǎn)"位置達(dá)到最低。通過模擬研究,得到優(yōu)化的PM2.5/PM10檢測(cè)系統(tǒng)物性參數(shù),即入口速度設(shè)定為0.5m/s~(-1)m/s最為合適,并且可以利用高分子減阻劑將檢測(cè)池中電解質(zhì)溶液的液體粘度調(diào)整為1×10~(-5)Pa·s,液體密度調(diào)整為1500kg/m~3,表面張力調(diào)整為0.065N/m。
[Abstract]:With the rapid development of economy, the phenomenon of haze is becoming more and more serious all over the world. The PM2.5/PM10 microparticles in haze are harmful to human health, so it is necessary to detect the concentration of PM2.5/PM10 particles in air. In this paper, a PM2.5/PM10 concentration monitoring system based on quartz crystal microbalance and dielectrophoresisDep is proposed. In order to improve the monitoring accuracy of PM2.5/PM10 concentration monitoring system and realize the system to monitor the concentration of two kinds of PM2.5/PM10 particles separately. In this paper, the motion characteristics of PM2.5/PM10 microparticles in the monitoring system are numerically simulated by the coupling of discrete Phase Model (DPM) and fluid volume of fluid volume (VVF). In this paper, the position of particle movement closest to the bottom of the detection cell is called the "settlement point" of the particle. In the simulation of the motion trajectory of microparticles in the solid-liquid two-phase flow model, the viscosity and density of the liquid are studied, respectively. The effect of inlet velocity factor on the trajectory of microparticles shows that when the viscosity of the liquid decreases from 0.01 Pa 路s to 1 脳 10 ~ (-4) Pa 路s, the "settlement point" of the particles decreases with the decrease of the viscosity of the liquid, while the viscosity of the liquid decreases from 1 脳 10 ~ (-4) Pa 路s to 1 脳 10 ~ (-6) Pa 路s. The position of settling point increased slightly with the decrease of liquid viscosity, and decreased slightly with the decrease of liquid density during the increase of liquid density from 500 kg / m ~ (3) to 2 500 kg / m ~ (-3). In the process of increasing the inlet velocity from 0.2 m / s to 10 m / s, the moving trajectory of particles with different diameters became larger and the "settlement point" position increased. On the basis of solid-liquid two-phase flow, The effects of inlet velocity, liquid viscosity, liquid density and surface tension of gas-liquid two-phase in gas-liquid-solid three-phase flow were studied by VOF DPM coupling model. The results show that when the inlet velocity increases from 0.2 m / s to 2 m / s, the moving trajectory separation degree of different diameter microparticles increases continuously. The position of "settlement point" of PM2.5 particle increases with the increase of inlet velocity. The position of "settlement point" of PM10 particle decreases first and then rises with the increase of inlet velocity, while the viscosity of liquid decreases from 0.001 Pa 路s to 1 脳 10 ~ (-6) Pa 路s. When the liquid density increased from 500 kg / m ~ (3) to 2000 kg / m ~ (3), the position of "settling point" decreased first and then increased. At 1500 kg 路m ~ (-3) ~ 3:00, the "settlement point" had a lowest position. The variation of gas-liquid two-phase surface tension also has a regular effect on the movement of microparticles. When the surface tension is 0.065 N / m, the settlement point of the particles reaches the lowest. The physical parameters of the optimized PM2.5/PM10 detection system are obtained by simulation. That is to say, the inlet velocity of 0.5 m / s / s is the most suitable, and the viscosity of electrolyte solution in the cell can be adjusted to 1 脳 10 ~ (-5) Pa 路s, the density of liquid to 1 500 kg / m ~ (3) and the surface tension to 0.065 N / m ~ (-1) by using polymer drag reducing agent.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：X513

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