共查询到19条相似文献,搜索用时 312 毫秒
1.
环状出口气泡雾化喷嘴研究 总被引:3,自引:0,他引:3
本文对环状出口气泡雾化喷嘴出口下游液膜的破碎过程进行了研究,发现气体的介入是促使液膜破碎的主要原因。利用DUALPDA对其下游流场的速度分布、颗粒直径分布以及通量分布进行了实验测量。发现喷嘴出口附近主流区域存在大量具有负向速度的颗粒,并且此处的颗粒平均直径显著减小,为气泡雾化机理提供了佐证;在喷嘴出口下游轴心处液雾呈现逆向流动趋势,证明此处存在负压回流;沿轴向的速度分布曲线与颗粒直径分布曲线的变化趋势说明气泡"爆炸"发生在出口下游5-15 mm距离内。 相似文献
2.
3.
石灰浆液喷嘴雾化特性 总被引:3,自引:0,他引:3
石灰浆液雾化喷嘴是烟气喷雾干燥净化系统的关键设备.利用Win212-2型激光粒度分析仪,对外混及内-外混相结合双流体石灰浆液喷嘴的雾化特性进行了试验研究,分析了气液质量比、石灰浆液浓度等参数对雾化粒径分布和雾化角的影响规律.结果表明,气液质量比增大,浆液液滴平均直径减小,但当气液比增大到一定值后,粒径变化趋于平缓;浆液浓度增加,液滴平均直径增加;气液质量比增加,雾化角减小. 相似文献
4.
《工程热物理学报》2020,(2)
利用高速摄像机获得顶部浸没方式下管口处气泡膨胀脱离过程,对比分析了管径、气体流量和管口浸没深度对气泡脱离直径和膨胀脱离时间的影响规律;运用三维流体体积(VOF)模型,模拟研究了气泡膨胀脱离过程中气泡膨胀脱离时间、脱离直径和气泡形态的变化规律,分析了气液湍动能和流场速度的分布变化规律。经过对比,实验结果与模拟结果一致。研究结果发现,气泡膨胀脱离时间随管径的增大而增加;随液体密度的增加而减小;随气体流量增大而降低,但降低速率逐渐减小.气泡脱离直径随气体流量的增加而增加且存在气泡脱离形态变化点;随管口浸没深度和液体密度的增加呈现下降趋势。气泡长短轴比随液体密度增大而增大,而随膨胀脱离时间的增加呈现降低趋势. 相似文献
5.
6.
7.
8.
《工程热物理学报》2017,(6)
本文基于Mixture模型,以油雾-空气混合物为研究对象,运用Fluent软件数值计算重载机车齿轮箱径向迷宫密封的内部流场和泄漏量,研究径向迷宫的密封机理,分析节流齿啮合深度对密封性能的影响,对比研究不同的油雾参数(油雾颗粒直径、体积分数)和密封结构参数(径向间隙、节流齿厚度)对介质高速通道的形成和迷宫密封性能的影响规律。研究结果表明;径向迷宫密封在节流齿相对啮合深度为0.5时形成与迷宫结构相适应的介质高速通道,径向间隙和节流齿厚度对介质高速通道的形成无影响,介质高速通道的形成仅取决于空腔宽度(即节流齿相对啮合深度),最佳相对啮合深度为0。径向间隙增大、节流齿厚度减小,高速通道效果更明显。随着油雾颗粒直径或径向间隙的增大,油雾体积分数或节流齿厚度的减小,迷宫泄漏量增加,密封性能减弱。 相似文献
9.
水平管气液两相泡状流紊流结构的准三维测量 总被引:2,自引:0,他引:2
用两个X型热膜探针对内径为35mm的水平管内气液两相泡状流的三维紊流结构进行了准三维测量,得出了沿不同直径的轴向、径向和周向的紊流脉动速度和雷诺应力分布。发现在水平管下部脉动速度和雷诺应力与单相流动时的分布规律相似;在管子上部由于空气泡的存在增强了脉动速度;在某些区域内,周向的脉动值甚至比径向和轴向的相应值还要高。水平气液两相泡状流中雷诺应力-uw不为零,在管子的上部甚至和-uv有相同的量级。给出了由于气泡引起的紊流脉动与总素流脉动比值沿径向的分布。 相似文献
10.
为实现高湿环境下脱硫塔内复杂烟气的高效除尘,设计了一种预混式双流体静电雾化喷嘴,并对其喷雾特性及荷电性能进行了试验研究。试验测量了喷雾粒径、锥角和荷质比等参数,通过量纲分析,得到了该喷嘴粒径分布与雷诺数Re的数学模型。试验结果表明:喷雾粒径随气液比(GLR)的增加呈指数减小,当气液比小于0.1时,喷雾粒径随气液比增加迅速减小,当气液比大于0.1时,喷雾粒径减小幅度趋于平缓;喷雾粒径随雷诺数的增加呈线性减小。喷雾锥角随着气液比增加呈先增大后减小的趋势,当气液比为0.1时喷雾锥角最大。气液比增加,喷雾荷质比增加,荷电效果逐渐增强。荷电电压的升高使得喷雾的单分散性提高,弥散空间逐渐增加。 相似文献
11.
12.
13.
在KIVA-3V中增加了油滴碰撞热多孔介质壁面的碰撞模型、传热模型及空心喷雾的线性不稳定性液膜破碎模型(LISA).在多孔介质结构简化描述的基础上,详细模拟了实心喷雾与空心锥形油雾与热多孔介质之间的碰撞过程.针对Senda等人的实验进行了数值计算,油束碰壁后油滴和油蒸汽分布的数值计算结果与实验结果吻合得很好.计算结果表明油雾在碰撞到热多孔介质后,油束会发生分裂,为油滴的快速蒸发和油蒸汽与空气充分混合创造了前提.油滴初始动能相同的条件下,空心喷雾的油滴穿越多孔介质的可能性比实心喷雾要小. 相似文献
14.
Matthieu Lecompte Christophe Dumouchel 《Particle & Particle Systems Characterization》2008,25(2):154-167
The three‐parameter, Generalized Gamma function solution of a recent MEF formulation used to derive liquid spray drop‐size distribution, is applied to sprays resulting from three different atomization processes. The objectives of these applications are to determine the sign of the parameters for which this function reports a more reliable fit and to further understand the parameter stability problem reported elsewhere. It is found that the lack of stability of the parameters is related to a characteristic feature of the mathematical function and appears for a series of spray drop‐size distributions with constant shape. For each situation analyzed in the present study, the Generalized Gamma function provides a very good fit with parameters that are either constant or correlated to the working conditions. As far as the sign of the parameters is concerned, the results show that the best formulation is a function of the spray and that it is impossible to know, a priori, which parameter sign will report the best fit. Finally, for one situation, it is found that the Generalized Gamma function allows extrapolation of drop sizes outside the measured values. All of the results converge to conclude that the three‐parameter Generalized Gamma function, which is identical to the well‐known Nukiyama‐Tanasawa distribution, accumulates valuable attributes to represent liquid spray drop‐size distributions. 相似文献
15.
Auto-ignition of a polydisperse fuel spray 总被引:1,自引:0,他引:1
Viatcheslav Bykov Igor Goldfarb Vladimir Goldshtein J. Barry Greenberg 《Proceedings of the Combustion Institute》2007,31(2):2257-2264
In the present paper, the effect of fuel spray polydispersity on the auto-ignition process in a fuel cloud is considered. In many engineering applications it is common practice to relate to the actual polydisperse spray as being equivalent to a monodisperse spray with all droplets therein having some average diameter. In combustion systems, the Sauter mean diameter (SMD) is frequently used for this purpose; it is based on the ratio between the total droplet volume and the total droplet surface area of all the droplets in the polydisperse spray. The main purpose of the current work is to examine qualitatively the dynamics of ignition of a truly polydisperse spray in a combustible gas medium and compare it with the dynamics of an equivalent monodisperse spray based on the SMD. Since the system of governing equations represents a multi-scale problem the method of integral manifolds is applied in order to extract the dynamical behavior. Preliminary computed results suggest that the use of the usual SMD-based monodisperse spray leads to quite a significant over-estimate of the ignition time. An alternative modified definition of the SMD, in which the overall liquid fuel volume is also conserved in the averaging process, reduces the discrepancy between the ignition time for the polydisperse spray and that of the equivalent monodisperse spray. However, it seems that some other sort of average droplet size needs to be determined to minimize the aforementioned discrepancy. These results highlight the care that must be exercised before dispensing with the behavior of the actual polydisperse spray in favor of that of an equivalent monodisperse spray, even at the expense of complexity. 相似文献
16.
17.
18.
19.
From the pressure balance condition on the free surface of a conducting liquid charged drop, an expression is derived for the equilibrium shape of the drop placed in the field of centrifugal forces acting in the tornado wall. The analysis is carried out in an approximation quadratic in small parameter (the ratio of the deformation amplitude to the radius of the initially spherical drop). In the linear approximation, the drop is a spheroid oblate in the direction normal to the tornado axis. The eccentricity of the spheroid squared is proportional to the angular velocity squared and the radius of the drop cubed. In the quadratic approximation, the equilibrium shape of the drop is other than spheroidal. 相似文献