双路离心式喷嘴雾化锥角的数值研究

利用Fluent软件,基于VOF（Volume—Of—Fluid）两相流模型对双路离心式喷嘴内的气液两相流动进行三维数值模拟。分别模拟喷嘴主油路单独供油、副油路单独供油与主副油路同时供油时雾化锥角,计算较好扑获了燃油在离心式喷嘴内所形成的空气涡及雾化锥角,所得喷嘴内压力分布、速度分布、相分布与雾化锥角,反映出该双路离心式喷嘴内流动特点,将计算结果与试验结果进行了对比分析。     

转炉蒸发冷却器内喷嘴雾化介质选择的数值模拟

针对转炉蒸发冷却系统内气液外混双相流喷嘴雾化介质的选择,应用计算流体力学,通过FLUENT模块主要运用VOF模型在不同压力工况下对雾化介质为水蒸气和氮气时外混喷嘴的气液流动状态进行数值模拟,通过模型x=0截面的速度云图及矢量图观测计算模拟结果,并以条件雾化角θ、质量平均直径d_(MMD)和索太尔平均直径d_(SMD)为雾化质量的判断标准。所得水蒸气雾化介质下的平均θ为74.43°,d_(MMD)为32.14μm,d_(SMD)为64.99μm;氮气雾化介质条件下的平均θ为68.13°,d_(MMD)为24.48μm,d_(SMD)为65.10μm。对三个判断标准和雾化质量的相关性进行分析,最终建议气液压力比为2的条件下,雾化介质采用氮气。     

空气雾化燃油喷嘴的喷雾数值模拟

利用Fluent商业软件对空气雾化喷嘴的喷雾场进行了模拟求解，讨论了喷嘴的结构对雾化效果的影响，并分析了喷嘴出口下游截面雾化粒径的分布情况。得出的结论表明喷嘴结构是影响雾化质量的重要因素之一，并且喷嘴下游截面粒径分布基本呈轴对称增大的趋势。     

气动喷嘴雾化特性的数值研究

对于内混式喷嘴,气液存在强烈的混合作用,决定雾化性能的最主要因素是作为雾化剂的高速气体与作为雾化介质的液体进行动量交换的强度。对气动喷嘴的雾化特性进行了数值模拟,对喷嘴内的流动现象进行了分析,得到了一些有益的结论。     

一体化除氧器弹簧喷嘴分析

弹簧喷嘴适应于机组变负荷运行的特点,使其在滑压运行除氧器中得到了广泛的应用,尤其是在一体化除氧器中更具有显著的优越性,能够维持恒定的喷射速度、喷射角度以及良好的雾化效果。介绍了一体化除氧器弹簧喷嘴的结构和原理,分析了弹簧喷嘴的喷流特性以及影响其雾化过程的因素,以期为一体化除氧器及其弹簧喷嘴的研究和实际应用提供一定的指导和参考。     

空气辅助雾化喷嘴的数值模拟研究

基于欧拉-拉格朗日两相流模型,数值模拟研究了一种带有螺纹通道的空气辅助雾化喷嘴的雾化过程。分析了喷嘴内空气流动特性和雾化场中的雾化特性,结果表明喷嘴内空气速度、压力和温度等参数随着流动截面变化时会发生剧烈变化,并在喷嘴出口处达到超音速状态,雾化场中雾滴具有较大的轴向速度和较小的径向速度,雾滴直径分布均匀,雾化效果良好。     

扇形喷嘴射流行为的数值模拟研究

以高压扇形喷嘴射流行为为研究对象,建立了描述扇形喷嘴射流行为的三维数学模型,采用数值模拟方法对不同入口压力、收缩角和V型切槽半角条件下扇形喷嘴射流特性进行研究.研究结果表明:当扇形喷嘴几何参数不变时,随着入口压力增加,射流冲击核心区域内水的流速显著增加,射流冲击宽度变化不显著;随着V型切槽半角的增加,射流冲击核心区域内...     

某型喷嘴流量特性的数值模拟

本文以某内混式气动喷嘴为研究对象,对喷嘴内部的气液双相流动进行了数值模拟,通过对计算结果的分析研究了该喷嘴气体和液体的流量特性,为今后相关喷嘴的设计工作奠定了一定的基础。     

喷嘴雾化技术进展

喷嘴的雾化技术具有很广泛的应用领域，主要针对液态燃料的雾化，分别从其雾化机理、雾化方法、液雾的测试技术以及燃油雾化的数值模拟技术等方面对雾化技术进行了简要的说明。     

抽水蓄能电站同发同抽水力特性VOF数值模拟

为了有效缓解电网突然出现的电力不平衡现象,同一个抽水蓄能电站不同水力单元机组同时分别发电及抽水运行,是对抽水蓄能运行及调度方式的一个重大创新措施。以某抽水蓄能电站上库为例,通过数学模型研究上库进/出水口在同发同抽工况下的库区水流流态、流道的水力特性、库区漩涡特性等水力参数的变化规律。结果表明,VOF方法可很好地模拟抽水蓄能同发同抽过程;同发同抽工况下,库区内进出水口附近局部水流流态与单向运行工况基本一致,但是两进/出水口之间形成连通的水流通道,库区内形成大范围横向流动,致使抽水单元大部分水流再次进入发电单元。     

Numerical simulation of spray performance based on the Euler-Lagrange approach

Numerical simulations have been carried out to investigate the liquid atomization and spray process using the Discrete Phase Model of the commercial CFD code combined with the Wall-Film boundary conditions. The effects of spray parameters on droplets Sauter mean diameter (SMD), droplet collision speed, the thickness of liquid-film, the surface temperature and its uniformity were analyzed in the present study. The simulation results and the experimental data obtained in the available literature agree within 13.8%. The computational results show that the spray pressure is the main factor to realize the atomization. Increasing the mass flux and the spray pressure, the droplet collision speed increases while the corresponding maximum film thickness on the heated surface declines. The surface temperature changes indistinctively with the increase of the spray distance, but the temperature distribution tends to be uniform.     

利用移动网格技术模拟冰融化过程中的传热问题

用计算流体动力学中的贴体坐标下移动网格技术分析了一类典型具有移动界面的流动融化传热问题,即Stefan问题。流场的计算采用控制容积法,控制方程的离散扩散项采用中心差分法,对流项采用QUICK格式。通过计算表明,这种技术可以非常好地捕捉由于融化引起的界面运动和变形的位置,能获得准确的融化曲线及温度场的演化过程。从中可总结出努谢尔特效或传热系数的变化趋势,找出在自然对流情况下,方冰柱的融化规律和固液界面形状的变化。     

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。     

Numerical simulation on liquid jet behavior issued into still air

Numerical simulations have been conducted to clarify the effects of turbulence, in the onset of protrusions on liquid jet surfaces. The turbulences in the liquid jet were simulated by the Rankin vortices. The liquid jet surface was tracked numerically by the VOF method. From numerical simulations, the protrusions on the liquid jet surface are induced by the vortices in the liquid, whose rotational direction decelerates the jet surface. Despite the distance between vortices, the displacement of the liquid jet surface from the initial surface location increases linearly, in time, at almost the same growth rate. In the initial region, the growth rate of the displacement increases as the major semiaxis‐to‐minor semiaxis ratio of the ellipsoidal vortex increases. The initial growth rate of displacement is almost proportional to the vortex intensity. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(2): 141–152, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10078     

Study on Characteristics of Different Types of Nozzles for Coal—Water Slurry Atomization

Three types of nozzles: a low-pressure multistage nozzle, an effervescent nozzle and a newly developed internal-mixing air-blast nozzle, for atomization of Coal-Water Slurry (CWS) were investigated. Influence of CWS properties including surface tension and apparent viscosity on atomization was studied. Comparisons among the nozzles were carried out in terms of spray droplet mean diameter and fuel output. Versatility of each nozzle was investigated and atomization mechanism of each nozzle was analyzed as well. The results showed that the newly developed internal-mixing air-blast nozzle has high fuel output and small mean droplet size in the spray, but the multistage nozzle has high versatility for handling of low quality CWS.     

Numerical simulation on the behavior of a liquid jet into an air flow

A numerical simulation has been performed to clarify the effects of turbulence in a liquid on the deformation of the liquid jet surface into an air flow. The turbulences in the liquid jet were simulated by the Rankin vortices, and the liquid jet surface was tracked numerically by the volume of fluid method. By numerical simulations, the onset of the protrusions on the liquid jet surface is caused by the vortices in the liquid, and the surrounding air flow plays an important role in the amplification of the protrusions. The amplification rate of the trough displacement is proportional to the air‐to‐liquid velocity ratio. At large imposed vortex intensities, the trough displacement increases with the vortex intensity. On the other hand, at small imposed vortex intensities, the amplification of the trough displacement is also affected by factors other than vortex intensity. © 2001 Scripta Technica, Heat Trans Asian Res, 30(6): 473–484, 2001