超声速气流中液体圆射流失稳与破碎机制的精细实验研究

The near-nozzle flow, which is a complex compressible two-phase fluid problem, plays a critical role in the breakup, atomization, and mixing for the liquid jet injected into a supersonic crossflow. The force, deformation and breakup of liquid jet are complicated and difficult to study. There is no deep understanding on the fine flow structures and flow mechanism in the area. Which has seriously delayed the research on the breakup mechanism and the simulation model of liquid jet in supersonic crossflows. The project intends to carry out the near-nozzle flow research on three progressive steps: "see the phenomenon", "get the law", and "deep study of the reasons". Firstly, based on the self-developed pulsed laser planar light source technology, focusing on near-nozzle area, multi-angle scattering imaging is carried out to study the representative flow phenomena and three-dimensional characteristics. Then, the near-nozzle flow law is quantitatively investigated. The generation and development of jet disturbance, the growth law of the unsteady jet structures, the stripping pattern and motion law of droplets are analyzed. Image recognition and matching methods are developed to study the motion acceleration law of near-nozzle flow structures. Finally, the surface pressure distribution and the law of the force of liquid column are analyzed. The correspondence between the action of the force and the deformation and acceleration of the flow structures is established. These will help to well understand the gas-liquid interaction mechanism and the physical reason of jet deformation in the near-nozzle area for the liquid jet injected into a supersonic crossflow. The project will promote the development of scramjet.

超声速气流中液体横向射流近场流动对射流破碎、雾化与混合的影响至关重要。近场流动属于复杂的可压缩两相流体界面问题，液体受力变形和破碎过程复杂，人们对该区域的精细流动现象和流动机理认识均不深入，严重影响了射流破碎机理研究和仿真破碎模型的建立。本项目拟从“看清样子”、“看懂规律”、“深究原因”三个方面递进开展近场流动研究。基于脉冲成像技术，聚焦近场开展多角度脉冲散射成像，结合CLSVOF仿真方法研究近场代表性的流动现象及流动三维特征。然后开展近场流动规律定量化研究，分析射流扰动产生发展和不稳定流动结构沿程增长规律，分析液滴从射流上的剥离方式和运动规律，发展图像识别和匹配方法研究近场流动结构的运动加速规律。最后分析射流沿程受力规律，建立力的作用与流动结构变形加速之间的对应关系，深入揭示近场气液相互作用机制，探究超声速气流中液体横向射流流动变形的物理根源。本项目研究能够为超燃冲压发动机研制提供指导。

本项目基于下吹式风洞在马赫数2.1来流条件下，开展了超声速气流中液体横向射流(Liquid Jet in Supersonic Crossflows,简称LJISC)的破碎雾化过程研究，聚焦喷孔近场细观结构，揭示了射流柱变形与破碎机理，掌握了破碎与雾化的内在规律。从“看清样子”、“看懂规律”、“深究原因”三个方面递进开展了近场流动研究。首先完善了基于脉冲成像技术、图像处理方法和数据分析方法，聚焦近场开展多角度脉冲散射成像，结合CLSVOF仿真方法研究近场代表性的流动现象及流动三维特征。然后开展了近场流动规律定量化研究，分析了射流扰动产生发展和不稳定流动结构沿程增长规律，分析液滴从射流上的剥离方式和运动规律，发展了图像识别和匹配方法，研究近场流动结构的运动加速规律。最后分析了射流沿程受力规律，深入揭示了近场气液相互作用机制和超声速气流中液体横向射流流动变形的物理根源。本项目研究能够为超燃冲压发动机研制提供指导。