火箭推进

气液针栓式喷嘴在变推力液体火箭中有重要应用。采取实验与数值计算结合的方法系统研究了不同环境压力下的针栓式喷嘴的液膜破碎过程、喷雾锥角、回流区分布、压力和液滴粒径分布等雾化特性,揭示了环境压力影响液膜破碎的3个因素:气流冲击、环境气体密度和环境压力对液膜挤压作用。结果表明:喷雾锥角会随环境压力增加而增大,但该趋势会随压力的增加而逐渐放缓。喷雾整体形态呈现锥形,喷雾中心区域存在低压回流区,回流区的液滴数目较少,但液滴粒径比较均匀。液滴主要分布在气液作用面,下游的液滴粒径较大,外部的液滴粒径比内部的大。液体火箭在启动的瞬间,燃烧室压力变化剧烈,可能导致喷雾锥角发生大幅变化,引起推进剂空间分布不均匀,对燃烧性能产生影响,因此要避免或减小较差雾化效果的燃烧室设计压力区间。

Gas-liquid pintle injector has important application in variable thrust liquid rocket. In order to study the influence of ambient pressure on the atomization characteristics of gas-liquid pintle injector, the atomization characteristics of the injector under different ambient pressures, such as the liquid film breaking process, spray cone angle, reflux zone distribution, pressure distribution and droplet size, were systematically studied by experiments and numerical computation. Three factors affecting liquid film breakage were revealed:airflow impact, ambient gas density and the effect of ambient pressure on liquid film extrusion. The results show that the spray cone angle increases with the increase of ambient pressure, but the increasing trend of spray cone angle decreases gradually. The overall shape of the spray is conical, and there is a low-pressure reflux area in the center of the spray. The number of droplets in the reflux area is small, but the particle size of droplets is relatively uniform. The droplets are mainly distributed on the gas-liquid interaction surface, and the particle size of the droplets downstream is larger, while the particle size of the droplets outside is larger than that of the droplets inside. At the moment when liquid rocket starts, the combustor pressure changes dramatically, which may lead to a large change in spray cone angle, resulting in uneven spatial distribution of propellant and affecting combustion performance. Therefore, it is necessary to avoid or reduce the design pressure interval of combustor with poor atomization.

引言
1 实验装置和计算方法
2 结果和讨论
3 结论

图1 气液针栓式喷嘴结构示意图<br/>Fig.1 Schematic of a gas-liquid pintle injector

图1 气液针栓式喷嘴结构示意图
Fig.1 Schematic of a gas-liquid pintle injector

表1 气液针栓式喷嘴的结构参数<br/>Tab.1 Dimensions of a gas-liquid pintle injector

表1 气液针栓式喷嘴的结构参数
Tab.1 Dimensions of a gas-liquid pintle injector

图2 不同环境压力下的气液针栓式喷嘴雾化特性测量系统<br/>Fig.2 Measurement system of the gas-liquid pintle injector under ambient pressure

图2 不同环境压力下的气液针栓式喷嘴雾化特性测量系统
Fig.2 Measurement system of the gas-liquid pintle injector under ambient pressure

图3 喷雾锥角处理流程<br/>Fig.3 Image processing of spray cone angle

图3 喷雾锥角处理流程
Fig.3 Image processing of spray cone angle

图4 三维数值计算网格示意图<br/>Fig.4 Three-dimensional sketch maps of the flow field mesh model

图4 三维数值计算网格示意图
Fig.4 Three-dimensional sketch maps of the flow field mesh model

图5 case(6,0)的喷雾图像<br/>Fig.5 Spray images with case(6,0)

图5 case(6,0)的喷雾图像
Fig.5 Spray images with case(6,0)

图6 case(6,0)的整体和局部放大喷雾图像<br/>Fig.6 The overall and detailed spray shape of case(6,0)

图6 case(6,0)的整体和局部放大喷雾图像
Fig.6 The overall and detailed spray shape of case(6,0)

图7 case(6,0)的速度和流场云图<br/>Fig.7 The velocity and streamline contour of case(6,0)

图7 case(6,0)的速度和流场云图
Fig.7 The velocity and streamline contour of case(6,0)

$图8 case(6,0)的yOz截面处水的体积分数<br/>Fig.8 The water volume fraction distribution of yOz plane of case(6,0)$

图8 case(6,0)的yOz截面处水的体积分数
Fig.8 The water volume fraction distribution of yOz plane of case(6,0)

图9 沿x轴的压力分布曲线<br/>Fig.9 Pressure distribution along the x-axis

图9 沿x轴的压力分布曲线
Fig.9 Pressure distribution along the x-axis

图10 沿y轴的液滴粒径分布<br/>Fig.10 Droplets diameter distribution along the y-axis

图10 沿y轴的液滴粒径分布
Fig.10 Droplets diameter distribution along the y-axis

图11 case(6,0)的液滴空间分布<br/>Fig.11 Droplets spatial distribution[case(6,0)]

图11 case(6,0)的液滴空间分布
Fig.11 Droplets spatial distribution[case(6,0)]

图12 不同环境压力下的喷雾图像(气体和液体流量保持固定)<br/>Fig.12 Spray images under different ambient pressure(mass flows of gas and liquid remain constant)

图12 不同环境压力下的喷雾图像(气体和液体流量保持固定)
Fig.12 Spray images under different ambient pressure(mass flows of gas and liquid remain constant)

图13 case(6,1)的整体和局部放大喷雾图像<br/>Fig.13 The overall and detailed spray shape of case(6,1)

图13 case(6,1)的整体和局部放大喷雾图像
Fig.13 The overall and detailed spray shape of case(6,1)

图14 case(6,1)的速度和流场云图<br/>Fig.14 The velocity and streamline contour of case(6,1)

图14 case(6,1)的速度和流场云图
Fig.14 The velocity and streamline contour of case(6,1)

图15 不同环境压力下的喷雾锥角曲线<br/>Fig.15 The spray cone angle under different ambient pressure

图15 不同环境压力下的喷雾锥角曲线
Fig.15 The spray cone angle under different ambient pressure

图16 液滴粒径的概率分布<br/>Fig.16 Probability density function(PDF)distribution of droplet diameter

图16 液滴粒径的概率分布
Fig.16 Probability density function(PDF)distribution of droplet diameter

表2 不同环境压力下的液滴粒径<br/>Tab.2 Droplet diameter under different ambient pressure

表2 不同环境压力下的液滴粒径
Tab.2 Droplet diameter under different ambient pressure

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备注

引言

1 实验装置和计算方法

2 结果和讨论

3 结论

期刊信息