Y型气流式喷嘴的雾化滴径和滴径分布

索特平均滴径(SMD)和滴径分布是描述喷嘴雾化性能的主要指标.根据Y型喷嘴雾化过程的特征,提出了Y型喷嘴的液滴随机分裂模型,得到了SMD的表达式.考察了Y型喷嘴对氯化聚氯乙烯(CPVC)氯化液的雾化过程,利用Mastersizer2000型测粒仪测定了雾化滴径分布.关联了SMD的经验方程,得到了初次雾化平均滴径.采用液滴随机分裂模型模拟计算了雾化滴径分布,计算结果与实验结果吻合,说明模型和平均滴径方程可以用来预测Y型喷嘴的雾化性能.     

三通道气流式喷嘴内粘性流体雾化过程

研究了粘性流体在三通道气流式喷嘴的雾化过程,考察了三通道喷嘴雾化性能的影响因素。实验及数值模拟结果表明,当其他条件不变时,雾化滴径随液体粘度的约0.088次方单调增大,随液体流量的约0.37次方单调增大,随一、三通道气量比α的增加,呈现先增后减的非单调变化趋势,在α≈0.22时Sauter平均直径SMD达到最大值。     

双通道气流式喷嘴雾化特性实验研究

以清水和空气为实验介质,对同轴双通道气流式喷嘴雾化特性进行了实验研究,分析了喷淋量对雾化角及径向流通量分布的影响,分别考察了气速和喷嘴轴向位置对液滴索特平均直径(SMD)的影响。研究结果表明,喷嘴径向流通量分布随着雾化气量的升高而趋于集中,当气体流量高于1500 L/min时,雾化角随着气量升高而降低;喷口处气速与喷嘴轴向位置均是影响液滴SMD与粒径分布的重要因素,液滴SMD随着气速增大逐渐减小,当气速超过150 m/s时其下降趋势变缓,粒径分布均匀度显著提高;随着喷嘴轴向距离增大液滴SMD逐渐减小,当距离大于300 mm时其变化不再显著,但粒径分布均匀度显著提高。     

气流式雾化实验研究进展

气流式雾化实验研究进展贺文智，陈宇峰，孟庆（内蒙古工业大学化工系）（内蒙古石化监督检验测试所）大量的资料［１，２］等表明液体雾化技术广泛应用于工程实际及科学研究领域中。对液体雾化过程的研究可大致分为液体雾化机理的研究与在雾化机理指导下的雾化过程的实验...     

预膜气流式雾化器的结构尺寸对雾化结果的影响

本文研究了预膜气流式雾化器的结构参数对雾化性能的影响,采用４种具有不同气液冲击角的二流式嘴,改变液体预膜通道 尺寸,以寻求在较小的能耗下,获得良好雾化效果的喷嘴设计参数。     

同轴双通道气流式雾化喷嘴初次雾化过程

对同轴双通道气流式雾化喷嘴的初次雾化过程进行了实验研究,发现在初次雾化过程中,初始微小扰动经过一段距离（即未扰动长度）后,在液体射流表面发展成为可以观察到的不稳定波.当气速U_g超过一临界值（大约25 m·s^-1）时,在不稳定波的波峰附近,形成小的突起,这些突起迅速被拉成细长液丝,液丝进一步破裂成液滴,最终导致液体的初次雾化.同时得到不稳定波长λ_m与环隙通道出口气速U_g、中心通道出口水速U_L的关系为λ_m＝68.60 U^-0.79_gU^-0.24_L;未扰动长度L_u与气速U_g、水速U_L的关系为L_u＝783.8 U^-1.54_gU^-0.16_L.     

气流式喷嘴雾化性能的研究

以国内应用较广的大直径液体喷嘴为研究对象,选择若干影响喷嘴雾化性能的液气质量流量比M_L/M_G、气体密度ρ_G、液体喷嘴孔直径D_L、气体出口面积A_G为主要参变量进行实验研究。通过大量实验,关联出计算液滴尺寸的准数方程式,为工业喷嘴的设计提供了重要的理论依据。     

雾滴空间分布的实验研究：气流旋转角度对雾滴分布的影响

本文用气流可高速旋转且旋转角度可改变的二流式喷嘴对描述雾滴在空间的质量分布特性的参数ｑ＾〔１〕与Ｊ＾〔２〕进行了实验测定。基于液体单元的受力情况,研究了气流旋转角度对雾滴在空间分布状态的影响。     

大液气质量流量比双通道气流式喷嘴雾化滴径

在气流式雾化过程的有限随机分裂模型基础上,结合液滴分裂时间和液滴运动规律,分析了大液气质量流量比同轴双通道气流式喷嘴的雾化过程,得到了Sauter平均直径（SMD）的一般表达式.实验结果表明,得到的SMD的关系式的形式是合理的,通过实验确定相关模型参数后,可以用来预测大液气质量流量比条件下同轴双通道气流式喷嘴的雾化性能.     

德士古双通道气流雾化喷嘴喷雾性能研究

针对以渣油为原料生产合成气的气化炉在现行生产中存在的雾化效果不良问题,研究了各影响因素的变化与双通道气流雾化喷嘴喷雾效果的关系。为优化雾化设计条件提供了依据。     

An atomization model for splash plate nozzles

A model for the atomization and spray formation by splash plate nozzles is presented. This model is based on the liquid sheet formation theory due to an oblique impingement of a liquid jet on a solid surface. The continuous liquid sheet formed by the jet impingement is replaced with a set of dispersed droplets. The initial droplet sizes and velocities are determined based on theoretically predicted liquid sheet thickness and velocity. A Lagrangian spray code is used to model the spray dynamics and droplet size distribution further downstream of the nozzle. Results of this model are confirmed by the experimental data on the droplet size distribution across the spray. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

基于VOF-DPM的气体辅助式污泥雾化破碎的数值模拟

为实现污泥雾化破碎的数值模拟,探究污泥雾化特征和操作参数对污泥雾化效果的影响,在污泥雾化试验平台试验的基础上基于Fluent软件对污泥在气体辅助式雾化器的雾化破碎进行模拟研究,模拟结果确定了污泥的雾化特征和最优操作参数。通过耦合流体体积法(VOF)与离散相模型(DPM),对较大的液体团采用VOF方法直接求解,对小液滴采用双向耦合的离散相模型进行追踪,能最大程度地提高计算的准确性。结果表明,污泥的密度和黏度随着含水率升高逐渐降低,气体速度、气液比和雾化角度是影响污泥雾化破碎的最重要的三个操作参数。在雾化过程中,中心区域的雾滴密度大于边缘区域且有少量大颗粒的聚集。对于含水率为87%、密度为1.065×103 kg/m3的污泥,在风速为180 m/s,气液比为126.3,雾化角度为55°时雾化效果最佳,雾滴颗粒的平均粒径约为0.193 mm,试验结果与模拟结果的颗粒粒径吻合度较好,最大相对误差为5.80%。     

A unified theoretical model for breakup of bubbles and droplets in turbulent flows

Pressure has a significant effect on bubble breakup, and bubbles and droplets have very different breakup behaviors. This work aimed to propose a unified breakup model for both bubbles and droplets including the effect of pressure. A mechanism analysis was made on the internal flow through the bubble/droplet neck in the breakup process, and a mathematical model was obtained based on the Young–Laplace and Bernoulli equations. The internal flow behavior strongly depended on the pressure or gas density, and based on this mechanism, a unified breakup model was proposed for both bubbles and droplets. For the first time, this unified breakup model gave good predictions of both the effect of pressure or gas density on the bubble breakup rate and the different daughter size distributions of bubbles and droplets. The effect of the mother bubble/droplet diameter, turbulent energy dissipation rate and surface tension on the breakup rate, and daughter bubble/droplet size distribution was discussed. This bubble breakup model can be further used in a population balance model (PBM) to study the effect of pressure on the bubble size distribution and in a computational fluid dynamics‐population balance model (CFD‐PBM) coupled model to study the hydrodynamic behaviors of a bubble column at elevated pressures. © 2014 American Institute of Chemical Engineers AIChE J, 61: 1391–1403, 2015     

引射雾化喷嘴性能研究

对新型引射雾化喷嘴的流量系数、雾化角、雾粒分布均匀性进行了研究,提出了喷嘴流量系数、雾化角、雾粒大小计算方法。研究表明,这些方法的计算结果与实际很接近,对新型引射雾化喷嘴的设计计算十分有益,具有重要的工程意义。     

同轴四通道喷嘴气流式雾化特性影响因素研究

提出一种新型同轴四通道喷嘴——由内到外采用气-液-气-液设置,最外环液体可以将合成气和氧气隔离,大幅降低喷嘴出口温度,可望延长气化炉中喷嘴使用寿命。为研究喷嘴雾化效果的影响因素,以水和空气为介质,利用马尔文激光粒度分析仪对同轴四通道喷嘴的气流式雾化液滴索特平均直径进行实验研究。发现对雾化效果影响程度从大到小依次为通道三、通道四、通道二和通道一;增大通道二、四液量分配比可以降低雾化粒径;增大外环液膜厚度会增大雾化粒径;通道一、三气量分配比对雾化颗粒的影响是非单调性的,雾化粒径先增大后减小。基于实验结果进行数值分析,拟合获得了同轴四通道喷嘴雾化液滴粒径关系式。     

Interface‐shrinkage‐driven breakup of droplets in microdevices with different dispersed fluid channel shape

A new droplet breakup mechanism is previously proposed—interface‐shrinkage‐driven breakup. In coaxial microdevices, when the contact angle between the continuous phase and dispersed fluid channel (DFC) is sufficiently low, the new mechanism instead of the classic shear‐driven mechanism dominates the breakup. The present study further investigated the new mechanism in microdevices with DFCs of different shape. Critical contact angles in different devices were determined by theoretical analysis and verified by experiments. It was found that the critical contact angle for the new mechanism depends on the shape of the DFC. The droplet size was measured for different devices when the new mechanism dominated the breakup. In contrast to the case for the shear‐driven mechanism, the droplet size is little affected by the capillary number. Mathematical models were established to predict the droplet size in different devices and results were found to agree well with experimental results. © 2017 American Institute of Chemical Engineers AIChE J, 63: 367–375, 2018     

Relationship between the size of mist droplets and ethanol condensation efficiency at ultrasonic atomization on ethanol–water mixtures

High‐frequency (2.4 MHz) ultrasonic irradiation to an ethanol–water mixture can induce the generation of ethanol‐rich mist droplets at lower temperatures. Two groups of droplets in micrometer‐ and nanometer‐sized were observed in the mist generated by the ultrasonic atomization. Nanosized droplets were considered to be ethanol‐rich droplets which cause ethanol condensation. © 2009 American Institute of Chemical Engineers AIChE J, 2010