The experimental study on the flow characteristics for a swirling gas–liquid spray atomizer

A new spray atomizer, that is, swirling gas–liquid spray atomizer, is presented in this paper based on the analysis of various air-assist atomizers and their atomization mechanism. The air-to-liquid mass flow rate ratio (ALR) of the atomizer during the hot-state tests is 4–6% (by compressed air for emulsified heavy oil). And it is of excellent atomization. The discharge coefficient and the spray cone angle of the atomizer are studied systematically. The influence factors considered are as follows: the structure parameters, ALR and the viscosity of the liquid. Through the experiments, the formula of discharge coefficient and the spray cone angle of the atomizer are given in the paper. And it can give good direction on the atomizer design. The atomizer can be employed in the industrial furnaces and other equipments where the liquid must be atomized.     

气泡喷嘴下游雾化与流场特性的研究

本文用激光粒子动态分析仪（ＰＤＡ）测量了水平喷射的气泡雾化喷嘴下游不同截面上的雾化液滴平均直径和速度分布，用水在常温，常压下进行试验，液体的喷射压力变化范围为１５０～５５０ｋＰａ；气液比的变化范围为０～０．１２。研究了随着喷射距离的增大，气泡喷嘴的雾化与流场特性的变化规律，试验结果表明，沿着喷射方向，与喷孔一定距离内，气泡喷嘴的液雾存在明显的扩散过程，气泡喷嘴的喷雾速度呈典型的抛物状分布，在喷雾轴     

Experimental investigations of spray generated by a pressure swirl atomizer

This paper has focused on the droplets behavior of kerosene RP-3 spray produced by a pressure swirl atomizers in terms of spray pattern, droplet size spatial distribution, mean droplet size, and distribution index with variations of pressure differential. The analyses have been carried out experimentally with the aid of optical diagnostic methods. The spray pattern, such as spray cone angle and fuel spatial distribution, has been measured by the technique of planar laser induced fluorescence of kerosene. A method for correction of fuel distribution measurement error induced by laser attenuation in spray is proposed and validated. The droplet size spatial distribution in central axis plane of the spray has been measured by a planar droplet sizing method which combining laser induced fluorescence and Mie scattering. The spray pattern in axial center plane and cross-sectional plane perpendicular to axis of the atomizer indicate that the droplets in spray concentrate around the outer periphery and in a narrow annular zone at the near-field of fuel injector exit, and then disperse to produce a solid spray at downstream of the spray. The analyses of droplet size spatial distribution, Sauter mean diameter, and distribution index with pressure differential clearly show the presence of droplets collision and its adverse effects on droplet size uniformity. The spray outline, droplet mass spatial distribution, and droplet size spatial distribution, droplets dispersion and collision in the process of atomization provide a great insight into the processes of atomization and spray development, which are key information for fuel injector design and quality control. The visualizations of spray pattern and droplet size spatial distribution with variations of pressure differential for pressure swirl atomizer are key issues in swirl cup or internally staged airblast fuel injectors because pressure swirl atomizer provides primary atomization or pilot spray which affects the quality of air/fuel mixing in lean-burn combustion. Moreover, a well-defined and complete database regarding the isothermal hollow cone spray is provided for validation of spray model.     

基于数值模拟的汽油机喷嘴结构优化CFD分析

以5WY-2817A汽油机喷嘴为研究对象,旨在提高该汽油机喷嘴流动特性,利用UG软件对喷嘴进行实体建模,通过喷雾稳态试验对模拟计算提供边界条件。利用AVL-FIRE软件进行喷嘴稳流三维数值计算,研究了不同压力室高度、喷孔分布直径和阀座锥角对喷孔处压力与速度的影响关系。研究结果表明,压力室高度0.2mm,喷孔分布直径1.4mm,阀座锥角43°时喷孔处燃油流动特性最佳。该结构优化可作为改善喷嘴雾化性能的最佳方案。     

小型直喷式柴油机喷雾特性的试验研究

为了掌握喷雾的结构物特性，利用高速摄像装置和高压容器拍摄了喷雾的逆光图像，并研究了喷雾周围介质压力对喷雾贯穿距离、喷雾锥角以及蒸发等喷雾特性的影响。在液滴数密度较大的条件下，燃料液滴的蒸发速率传热过程和雾化质量的影响；喷射妆期喷雾的贯穿距离和贯穿速度几乎不受介质物影响；喷雾的贯穿跨离受喷油压力的影响不大，但随着喷油压力的提高，喷雾锥角增大，喷雾质量得到改善。     

GDI发动机喷雾特性的数值模拟和试验

汽油直喷发动机高压燃油喷射系统与燃油经济性和废气排放等密切相关,通过试验和数值模拟对高压喷油系统和旋流喷油器的喷雾特性进行了研究.在不同喷射压力、背压压力条件下,利用高速摄像机对喷入定体积容器的喷雾进行了喷雾贯穿距离和喷雾锥角参数的测量.结果表明:在低背压压力下,喷雾呈现出空锥、较大范围的分布形态,有利于实现燃油与空气的均质混合;在高背压条件下,喷雾呈现出紧凑密集的分布形态,有利于实现燃油与空气的分层混合.获得的贯穿距离经验公式与试验测量值在一定范围内是一致的.基于AVL HYDSIM环境建立了一维高压喷油系统模型,模拟得到的针阀升程与试验获得的图像在时间上具有一致性.     

气泡雾化喷嘴在不同液体物性下的喷雾特性研究

利用PS-Ⅱ激光衍射粒度仪测量分析了气泡雾化喷嘴在雾化不同动力粘度，不同表面张力的液体时的特性，发现液体的粘性对于气泡雾化效果影响程度不大，随着动力粘度的增加，平均直径稍有增大，当动力粘度很高时由于泡状流更容易形成，所以平均直径有所减小，而液体表面张力的变化对于雾化质量的影响显。     

小流量旋流喷嘴喷雾性能影响因素的试验研究

在超高压燃油喷雾试验台上测试分析了不同环境背压及喷射流量对适用于斯特林发动机的小流量压力旋流喷嘴燃料喷射性能的影响。结果表明:喷嘴的喷雾形态受燃烧室背压的影响最明显,背压升高,喷雾锥角减小;喷射流量的影响受背压的限制,中高背压下,流量增大到一定程度后锥角开始变小,流量继续增大,雾化效果变差。喷嘴设计流量的影响为:增大设计流量,相同工况下的喷雾锥角有增大的趋势,但有效雾化的最小临界流量值变大;设计锥角的影响和设计流量类似:较大喷射流量工况下,大设计锥角喷嘴对高背压的适应性较好。研究认为:小流量工况只能采用小设计流量的喷嘴,且对高背压的适应性较差;在大流量工况下,设计流量和设计锥角均较大的喷嘴对高背压工况具有更好的适应性。     

Macroscopic spray behavior and atomization characteristics of refrigerant R22 injection under increased ambient pressure

In this study, we investigate the spray behavior and atomization characteristics of refrigerant R22 injection in a high pressure chamber under various ambient pressures using a spray visualization system and image processing. In order to observe the spray behavior of R22, the spray images were analyzed in time series after the start of injection. From the spray images, spray characteristics such as the spray tip penetration, cone angle and spray area were investigated by using the contour map of the light intensity levels. The results showed that the ambient pressure significantly affected the spray characteristics of the refrigerant. The spray tip penetration velocity was the highest at the ambient pressure of 500 kPa. When the ambient pressure was lower than 500 kPa, the vaporization of the refrigerant determined the spray and atomization characteristics; however, when ambient pressure was higher than 500 kPa, the surface tension and viscosity of the refrigerant and the density of ambient gas affected the spray behavior and atomization characteristics. Furthermore, the injection stream of the refrigerant was compared with the injection stream of water at the ambient pressure of 1500 kPa.     

环状出口气泡雾化喷嘴液膜破碎过程与喷雾特性

主要研究了环状出口气泡雾化喷嘴出口下游液膜破碎过程与喷雾特性．当气液质量流量比为零时，出口下游形成空心封闭膜壳，表面波明显存在于液膜表面．随着气液质量流量比的增加，膜壳逐渐膨胀并在最薄弱部位被撕裂．利用DualPDA测量得到液雾颗粒的速度分布、直径分布与流通量分布特性；在主流区域存在负向运动的粒子同时颗粒平均速度明显降低．出口下游的速度分布曲线呈现双峰趋势，实验数据显示中心回流区域结束于距离出口30mm左右．索特平均直径的有关数据显示气泡的“爆炸”发生于出口下游5～15mm区域．流通量分布曲线也是双峰的，径向逐渐扩张，轴向逐渐降低，并且液雾主流区域流通量明显高于边缘区域的流通量．     

引射比对生物柴油斯特林发动机喷雾特性影响的仿真研究

基于斯特林发动机的喷雾特性,建立了某斯特林发动机旋流引射、喷雾的数学物理模型,模拟了高背压下生物柴油斯特林发动机在不同引射比下的喷雾过程。研究发现:生物柴油喷雾锥角随引射比的增大而增大,大引射比下的喷雾油束前端出现了明显的凹型回缩锋面;引射比越大,喷雾贯穿距越小;增大引射比,液滴速度增大,索特平均直径减小,粒径方差减小。高背压下,增大引射比能增大燃油混合气的空间分布,提高喷雾雾化效果。     

气泡雾化喷嘴雾化性能的试验研究

在竖直向下喷射方式下,对三种不同结构尺寸的喷嘴的雾化特性及性能进行了试验研究。试验在常温常压下进行,液体采用水,雾化气为压缩空气,采用PIV技术来测量雾化颗粒的平均粒径。试验结果表明:增大气液质量流量比;增大空气注入截面积;在喷嘴的最大流量范围内,增大液体流量均可提高雾化质量。     

簇孔式喷油嘴喷雾雾化特性的研究进展

燃油喷雾雾化特性直接影响燃烧,从而也极大地影响了柴油机的各项性能,而喷嘴在很大程度上决定了燃油的喷雾雾化特性。本文基于现有研究文献,介绍了簇孔式喷油嘴的概念及其喷雾雾化特性,通过与传统单孔喷嘴的比较实验,阐述了簇孔式喷嘴的在喷雾贯穿距离,喷雾锥角,雾化能力等喷雾特性上的独特优势。这一新型喷嘴的提出与应用,对改善喷雾雾化与燃烧,提高发动机性能具有重大意义。     

Spray properties of alternative fuels: A comparative analysis of biodiesel and diesel

Physical properties of biodiesel play an important role in the injection, atomization and combustion performance. An experiment was carried out to investigate the spray properties of biodiesel. The experimental setup was based on an electronic unit‐pump (EUP) bench, a constant volume chamber and a high‐speed digital camera. The photographs of spray were dealt with by using an image processing procedure. Then the spray tip penetrations and cone angles were obtained and analyzed. The experimental results indicate that the spray tip penetrations and cone angles of biodiesel increase with increasing injection duration. In addition, with decreasing ambient pressure the spray tip penetrations increase while the cone angles decrease. Furthermore, ambient pressure has a stronger effect on the spray properties of biodiesel than injection pressure. On the macroscopically view, the shape of biodiesel spray is similar to that of diesel. The final tip penetrations and cone angles of biodiesel are greater than those of diesel due to its higher viscosity, density and bulk modulus. Copyright © 2008 John Wiley & Sons, Ltd.     

基于数字图像处理的LPG喷雾特性试验研究

使用高速纹影摄影和数字图像处理方法研究了具有相同喷孔直径的两个分别带有和不带双孔分流套的单喷孔喷嘴在MPI喷射条件下液态LPG燃料的自由喷雾过程,测量了喷雾贯穿距离、投影喷雾面积、喷雾体积和喷雾锥角等喷雾特性。通过与手工测量结果对比证明了数字图像处理方法测量结果的有效性。试验结果表明:喷射压力越高,喷雾贯穿距离、投影喷雾面积和喷雾体积越大,而喷雾锥角越小;带有双孔分流套的喷嘴雾化效果好,更有利于形成均匀混合气;在喷雾中期和后期,不带双孔分流套的喷嘴的喷雾贯穿距离长,但在喷雾初期的一段时间内,却比带有双孔分流套的喷嘴的喷雾贯穿距离短。     

Atomization performance and TG analysis of Fischer–Tropsch fuel compared with RP-3 aviation fuel

As many potential alternative jet fuels would be used in the in-service engine, such as the most promising Fischer–Tropsch (F–T) jet fuel, it's necessary to test their performance in compared with petroleum derived jet fuel. In this study, atomization performance of F–T fuel and traditional RP-3 jet fuel were assessed based on three parameters including Sauter mean diameter, Spray cone angle, and Distribution index N. Thermogravimetric (TG) analysis is also conducted for kinetics analysis. TG experiments of F–T fuel and RP-3 were carried out in order to establish the relationship between atomization and TG characteristics. Burnout index B_f and uniform parameter α derived based on TG experiments were defined in this study. The qualitative relationship between B_f, α and atomization parameters were given for rapid evaluation of alternative jet fuel's atomization characteristics.     

螺旋形实心锥喷嘴雾化特性试验研究

为了对氨法脱硫用螺旋形实心锥喷嘴的雾化特性进行准确预测,基于高速阴影技术和图像处理方法,对两种不同螺旋升角的螺旋形实心锥喷嘴的流量特性、喷雾场结构特征、雾化角变化规律、破碎长度、液滴空间分布及平均粒径进行分析。结合脱硫常用的空心锥离心式喷嘴,开展了两种喷嘴的稳定性对比分析。结果表明:螺旋形实心锥喷嘴的流量特性与螺旋升角无关,其喷雾场呈螺旋状同心锥面分布,雾化后液滴也呈螺旋形多层次分布,即实心锥分布;螺旋形实心锥喷嘴雾化角在喷注压降大于0.05 MPa时与螺旋形升角有关,与流量和喷注压降无关;考虑螺旋面升角对液滴平均粒径的影响,得到了新的索太尔平均直径(SMD)经验关系式,预测结果与试验结果趋势一致,且螺旋升角越大,液滴平均粒径越小;螺旋形实心锥喷嘴在喷注压降小于0.05 MPa时也能保证稳定雾化,而空心锥离心式喷嘴会出现约为9 Hz的自激振荡现象,喷雾场呈"宝塔形",且具有明显的Klystron效应。     

基于纹影法的高压柴油喷雾反射激波特性

使用某型柴油机燃烧室的截面拉伸模型,在其内部进行常温下的高压柴油喷射,通过纹影法研究诱导激波撞壁反射之后本身的运动特性以及对喷雾发展造成的影响,并与无燃烧室模型的试验数据对比.结果表明:诱导激波撞壁反射按照时间发展顺序主要分为3个类别;其中第一类反射激波主要影响喷雾横向扩散,会造成喷雾锥角相较于无激波工况减小,并且其抑制效果与喷射压力及背景压力均呈反比,同时,第一类反射激波两翼的运动不对称性也会造成喷雾明显偏离轴心,其偏轴程度与背景压力呈反比,与喷射压力无关.     

Influences of spray and operating parameters on penetration of vaporizing fuel droplets in a gas turbine combustor

The effects of inlet spray and operating parameters on penetration and vaporization histories of fuel droplets of a liquid fuel spray injected into a turbulent swirling flow of air through a typical can type gas turbine combustor, have been evaluated from numerical solutions of the conservation equations in gas and droplet phases. The computational scheme is based on the typical stochastic separated flow model of the gas-droplet flow within the combustor. A κ–ε model with wall function treatment for near wall region has been adopted for the solution of conservative equations in gas phase. The initial spray parameters are specified by a suitable PDF size distribution and a given spray cone angle. It has been recognized that the penetration of vaporizing droplets is reduced with an increase in inlet air swirl and spray cone angle. An increase in inlet air pressure or a decrease in inlet air temperature also results in a reduction in droplet penetration. The inlet air pressure and spray cone angle are found to be the most influencing parameters in this regard.     

Experimental study on spray characteristics of ethanol-aviation kerosene blended fuel with a high-pressure common rail injection system

Partial replacement of fossil fuels by biomass based alternative fuels is considered as a possible option toward sustainability in aviation applications. The present work aims to study the changes in the spray characteristics in a pressure vessel when operated with aviation kerosene and ethanol-aviation kerosene blended fuel in a high-pressure common rail injection system. This research proposes the concept of adding a certain percentage of ethanol to aviation kerosene, creating ethanol-aviation kerosene blended fuel, which can decrease our reliance on fossil fuels on some level. The spray characteristics of the blended fuel, like spray tip penetration, spray cone angle and spray area, are studied in our work. Through the analysis, we can find that the atomization conditions have a significant impact on the spray characteristics of the aviation kerosene. Similarly, the experimental results show that the addition of ethanol has certain effect on the spray characteristics of the aviation kerosene. And the empirical equations applied in this study to predicting spray tip penetration and spray tip velocity provide a good agreement with the experimental data in the error-allowed range.