背压对气液针栓单元喷雾分布特性的影响

Influence of backpressure on spray distribution characteristics of a gas-liquid pintle injector element

通过实验研究了径向孔型气液针栓单元在不同背压环境下的喷雾分布特性。搭建了可以提供0.1~6.0 MPa范围内的稳定背压并且具有多个光学测量窗口的常流式雾化实验系统,采用过滤水和干燥空气代替液氧和气甲烷进行了雾化实验。实验背压范围为0.1~1.5 MPa。采用背景光成像技术获得了气液针栓单元的喷雾图像,通过图像处理研究了喷雾形态及其空间分布。结果表明:气液针栓单元在背压环境中形成的喷雾扇内部充实,液雾浓密;喷雾边界具有明显的“折转”特征。根据喷雾的浓密分布将喷雾场分为3个区域:喷雾核心区、喷雾边界区和稀疏喷雾区。背压与局部动量比对喷雾径向空间分布范围的影响相反,背压越小、局部动量比越大,喷雾半锥角越大,喷雾迎风面边界轮廓线包络范围越大。此外,相比喷雾半锥角,喷雾迎风面边界轮廓线可以较好地说明喷嘴近场喷雾空间分布范围变化。

The spray distribution characteristics of a radial-orifice gas-liquid pintle injector element were studied by ex⁃periments in different backpressure environments.A normal flow cold atomization experimental system which can pro⁃vide stable backpressure in the range of 0.1-6.0 MPa and has multiple optical measurement windows was built.The atomization experiment was conducted by using filtered water and dry air instead of liquid oxygen and gas methane.The range of experimental backpressure was 0.1-1.5 MPa.The spray image of pintle injector element was obtained by using the background light imaging technology.The spray morphology and spatial distribution were studied by im⁃age processing.Results show that the spray formed by the gas-liquid pintle injector element in the backpressure envi⁃ronment was dense,and the spray boundary has obvious“turning”characteristic.According to the spray density dis⁃tribution,the spray field is divided into three zones:spray core zone,spray boundary zone,and sparse spray zone.The influences of backpressure and local momentum ratio on radial spatial distribution range of spray are opposite.The smaller the backpressure is,the larger the local momentum ratio is,the larger the spray half angle is and the larger the envelope range of the windward boundary contour of spray is.In addition,compared with the spray half angle,the windward boundary contour of spray can better show the change of the spray spatial distribution range in the near field of the nozzle.