水力喷射空气旋流器的气相压降特性及射流雾化研究

发布时间：2018-03-10 09:22

本文选题：水力喷射空气旋流器　切入点：气相压降特性　出处：《重庆理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：水力喷射空气旋流器(water-sparged aerocyclone,WSA)是一种利用液相射流在气相三维旋流场中的雾化现象,形成液体射流与气体旋流耦合场,同时又利用旋流场的静态超重力作用,实现强化气液传质和反应的新型传质反应设备。为了深入认识WSA中气液两相的作用机理,提出WSA中射流雾化的调控方法,本文采用实验研究,并结合数值模拟方法,系统地研究了WSA的气相压降特性与变化机制,以及WSA中射流雾化的传质面积与液滴尺寸。主要研究结论如下:1、WSA的气相压降随着进口气速的增大,会相继经历一个低压降区、压降突跳区和高压降区三个特征区域,而且WSA中液体射流的排列方式不会影响这种气相压降变化的规律,射流的充分雾化发生在高压降区域内。2、雷诺应力模型和VOF两相流模型能够较好地模拟WSA的气相压降特性和液相回流比。通过对三个不同气相压降区域的液相含率分布、射流流型的分析,提出了WSA气相压降突变的机理。在低压降区域(0ug7.11 m·s-1),射流与旋流场的相互影响较小,射流保持较完整的形态;在压降突跳区域(7.11ug8.89 m·s-1),射流主要表现为袋式破碎雾化机理,射流表面的质量被吹脱和袋式破碎雾化造成气相密度突然增大,引起了气相压降的突跳;在高压降区域(ug8.89 m·s-1),射流雾化逐渐转化为剪切破碎雾化机理。3、在射流旋流耦合场中,轴向速度随进口气速增大而增大。但当进口气速处于压降突跳区时,在接近旋流器壁面处轴向速度增加最大;旋流场的切向速度出现下降,并发生方向逆转;耦合场径向速度沿径向分布不对称性增大,速度方向也出现了逆转现象。4、在气相高压降区域里,射流雾化的传质面积随进口气速增大,先升高后下降,出现一个最大值。射流雾化传质面积较大时,进口气速一般需要超过压降突跳终点气速的50%~100%,这与气液两相流数值模拟得到的结果范围相近;射流雾化传质面积达到最大值时,进口气速需超过压降突跳终点气速的80%左右。在一定的进口速度下,随着射流速度的增大,比传质面积也相应地增大,而且当射流速度由低速向高速变化的过程中,传质面积的增大在低射流速度时增加的幅度较明显,在较高射流速度下传质面积增加较慢。5、WSA中液体射流在气相高压降区域中射流雾化的液滴尺寸,随着进口气速的增大逐渐减小,达到最小值后又开始增大。射流雾化液滴尺寸达到最小值时的进口气速约在超过压降突跳终点气速的100%。这与传质面积较大的区域出现在进口气速超过压降突跳终点气速的50%~100%的结论相吻合。在一定的进口气速下,射流速度增大有使射流雾化最小液滴尺寸增大的趋势。
[Abstract]:Jet air cyclone (water-sparged aerocyclone WSA) is a kind of phenomenon by liquid jet atomization in the gas phase in the formation of three-dimensional swirling flow, liquid jet and gas swirl coupling field, and using the super gravity field of static hydrocyclone, achieve new equipment to strengthen the gas-liquid mass transfer reaction mass transfer and reaction in order to effect. Understanding the mechanism of gas-liquid two-phase WSA, put forward the control method of WSA jet atomization, experimental study in this paper, combined with numerical simulation method, the system of WSA gas pressure drop characteristics and change mechanism, and the mass transfer area of WSA jet atomization and droplet size. The main conclusions are as follows: 1, with the inlet gas velocity increases WSA gas pressure drop, have experienced a low drop drop zone, jump three characteristics of regional area and pressure drop, and no liquid jet in the arrangement of the WSA A variation of the gas pressure drop, fully atomized jet high pressure drop occurred in the region of.2, the Reynolds stress model and VOF two-phase flow model can better simulate the WSA characteristics of gas pressure drop and liquid reflux ratio. The distribution rate of three different gas pressure drop zone liquid jet flow, analysis the flow pattern of the gas pressure drop, the mechanism of WSA mutation is proposed. In the low pressure drop region (0ug7.11 m s-1), the mutual influence small jet and swirling flow field of jet preserved form; jump region in the process pressure drop (7.11ug8.89 m s-1), mainly for the jet bag broken atomization mechanism, quality the jet surface is blowing and bag broken atomization caused by gas density increases suddenly, causing the gas pressure drop jump; pressure drop area (ug8.89 m s-1), jet atomization is gradually transformed into the shear atomization mechanism of.3, in the swirling coupling field, axial velocity. Gas velocity increases. But when the inlet gas velocity in the drop jump area, maximum increase near the cyclone wall axial velocity of swirling flow; the tangential velocity decreased and reversed direction; coupled radial velocity distribution along radial direction asymmetry increases, speed reversal phenomenon to the.4. In the gas phase pressure drop in the area and mass transfer area of jet atomization with inlet gas velocity increases, increased first and then decreased, there is a maximum value. The jet atomization mass transfer area is large, the inlet gas velocity generally requires more than drop jump end point gas velocity of 50%~ 100%, the gas-liquid two-phase flow numerical simulation results obtained range similar to jet atomization; mass transfer area reached the maximum value when the pressure drop around the inlet gas velocity required more than 80% jump end point gas velocity. At a certain inlet velocity, with the increase of jet velocity, ratio of mass transfer area is correspondingly increased, and When the jet velocity from low speed to high speed change, the increase in the mass transfer area of low jet velocity when the amplitude obviously increases slowly in.5 area of high jet velocity of mass transfer, droplet size, spray jet liquid jet WSA in the gas phase pressure drop in the region, with the increase of the inlet gas velocity gradually decreases, reaches a minimum value began to increase. The jet atomization droplet size reaches the minimum value when the inlet gas velocity is about over pressure drop jump end point gas velocity 100%. and the larger mass transfer area in the inlet gas velocity exceeds the pressure jump end point gas velocity 50%~100% is consistent with the conclusion. In a certain import the gas velocity, the jet velocity increases with the trend of the minimum jet atomization droplet size increases.

【学位授予单位】：重庆理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051.8

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