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Basic Studies on Spray Formation Mechanism and Its Modeling

喷雾形成机理及其建模的基础研究

基本信息

批准号：
12650189
负责人：
INAMURA Takao
金额：
$ 2.11万
依托单位：
Hirosaki University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12650189/
关键词：
Liquid Atomization Liquid Jet Disintegration Mechanism Numerical Simulation Instability Analysis Spray Characteristics Engine Fuel Injector Rocket Injector ロケット用噴射器

项目摘要

The purpose of this study is to clarify analytically and experimentally the disintegration process of disturbance waves generated on a liquid column surface near a nozzle exit by the shear force of the surrounding air, and is to generate the model of the spray formation which is used in the numerical simulation of a spray flow without the experimental data.At first, the growth rate of the disturbance wave on a liquid column surface was obtained by the linear instability theory as a function of the wave number with varying the relative velocity between the liquid column and the surrounding air. Next, the behaviors of the liquid column oscillated at the nozzle exit by the piezo-electric ceramic were observed by the photographs. The fluctuations of the spray concentration under the nozzle exit was measured by the light sheet method, and the relationship, between the frequency of the piezo-electric ceramic and that of the spray concentration fluctuation was obtained by the frequency analys … More is.Based on the results of above experimental analyzes, the model of the spray formation was newly developed, and the breakup length of a liquid column and the mean droplet size of the spray generated from the liquid column disintegration were calculated with using the proposed model. The calculation results were compared to the empirical equations. Consequently, the following results were obtained;(1) The wavelength of the disturbance wave with the maximum growth rate decreases linearly as the relative velocity increases on the log-log graph. The growth rate increases linearly as the relative velocity increases on the log-log graph.(2) In the case of the liquid column injection into the parallel air flow, at small air velocity the low frequency component near 5 kHz and the high frequency component near 10 kHz exit in the fluctuation component of the spray concentration. At large air velocity the high frequency component becomes intense. At further large air velocity all the frequency components appear.(3) The calculated breakup length using the proposed spray formation model is almost coincident with the empirical equation. The calculated mean droplet size almost coincides with the empirical equation except the condition of extremely small air velocity. Less

本研究的目的是从理论和实验两方面阐明喷嘴出口附近液柱表面受周围空气剪切力作用而产生的扰动波的破碎过程，并在没有实验数据的情况下建立用于喷雾流数值模拟的喷雾形成模型。利用线性不稳定性理论，得到了液柱表面扰动波的增长率随液柱与周围空气的相对速度变化的波数的函数关系。接着，通过照片观察在喷嘴出口处由压电陶瓷振荡的液柱的行为。采用片光法测量了喷嘴出口下的喷雾浓度波动，并通过频率分析得到了压电陶瓷频率与喷雾浓度波动频率之间的关系 ...更多信息基于上述实验分析的结果，新开发了喷雾形成的模型，并且使用所提出的模型计算了液柱的破碎长度和由液柱破碎产生的喷雾的平均液滴尺寸。将计算结果与经验公式进行了比较。结果表明：（1）在双对数坐标图上，扰动波最大增长率波长随相对速度的增加而线性减小。在双对数图上，生长速率随相对速度的增加而线性增加。(2)在液柱喷射到平行气流中的情况下，在小的空气速度下，在喷雾浓度的波动分量中存在5kHz附近的低频分量和10kHz附近的高频分量。在大风速下，高频分量变得强烈。在更大的空气流速下，所有的频率分量都出现。(3)用该模型计算的喷雾破碎长度与经验公式基本吻合。除风速很小的情况外，计算得到的液滴平均粒径与经验公式基本吻合。少