高温燃气射流作用下空泡界面演化与掺气机理研究

In this project, fundamental research on free surface evolution and gas entrainment mechanism for cavity with the effect of exhausted gas jet with high temperature and high speed will be carried out using integrated theoretical, numerical and experimental method. The optical measuring equipment including the high-speed camera, PIV and Particle/Droplet Image Analysis system will be adopted to capture the gas-liquid interphase, the jet-cavity interaction mechanism and the flow field parameter distributions. A compressive multiphase numerical model which takes the phase change effect into account will be established based on the free surface capturing model (VOF) and Large Eddy Simulation (LES) model. Based on that model, numerical simulation will be carried out to investigate the coupled flow field generated by gas jet and cavity. It is aim to reveal the detail flow field structure within and out of the cavity which is composed of multi-component hot gas, and give insights on the free surface revolution mechanism. The description method and computational model for free surface structure will be analyzed. Better understanding on the gas entrainment mechanism for the free surface under strong shear and turbulence will be obtained, based on which, the theoretical model for free surface gas entrainment will be constructed. Finally, the cavity control method based on the tail gas jet and the side gas jet will be provided to manipulate the cavity shape effectively, offering great theoretical and technological support for the engineering application of drag reduction technology by cavity.

本项目综合运用理论分析、数值模拟和实验测量手段，开展高温、高速燃气射流作用下空泡界面演化动力学与掺气机理研究。通过高速摄像、PIV和颗粒/液滴图像分析（PDIA）系统等高精度光学测量技术与方法，追踪高温、高速燃气射流作用下空泡界面的时变特性，总结燃气射流与空泡耦合作用机理及气液掺混区流场参数分布规律，够建耦合VOF界面追踪方法和大涡模拟（LES）的可压、多相流数学模型。阐明高温、多组分气体掺混空泡内外精细流动结构及形态演化动力学过程，建立空泡形态演化动力学描述方法与理论。揭示强剪切、高湍流度作用下掺气界面湍流细观流动结构和空泡的相互作用关系，构建相变界面掺气理论和模型，提出基于尾部燃气喷流和侧向燃气射流的空泡控制方法，实现空泡形态高效控制，为空泡减阻理论工程应用提供有力理论与技术支撑。

超空泡减阻和水冲压发动机技术为制约超空泡武器发展的核心关键技术。然而发动机尾喷流与超空泡外流紧密耦合，高速射流作用空泡界面易引发生变形甚至溃灭，给空泡形态准确预示带来较大难度。本项目综合运用理论分析、数值模拟和实验测量手段，开展高温、高速燃气射流作用下空泡界面演化动力学与掺气机理研究。.基于OpenFOAM平台建立了可压多相流求解器，耦合VOF界面追踪方法，RANS/LES混合多相湍流模型，实现了多相可压、多相共存和多种相变耦合模拟，典型工况计算误差小于15%；基于小型重力式自由射流水洞和固体燃气发生器等构建了空泡射流耦合作用实验系统，可实现高速冷射流、高温燃气和通气空泡耦合实验，准确追踪气液界面瞬态演化和压力场分布。研究表明高速射流对通气空泡存在完全补气、部分补气和完全泄气三种模式，流场对应表现为透明空泡、透明空泡-射流，震荡空泡-射流三种形态；基于实验和数值模拟构建了空泡射流形态随无量纲动量比、总压比、相对长度和相对直径四个参数变化的流型图；阐述了射流作用下三种典型的空泡失稳机制，包括：液体回射流冲击，空泡界面波动贴壁和压力波诱导，提出了基于尾流引射的空泡流动控制方法，获得了射流强度、弹体外形、航行深度等对尾流引射效应的影响规律，提出了通过外形设计和通气系统结合抑制空泡震荡的方法，并初步完成实验验证。.项目研究成果有助于丰富气液两相流理论体系，增强强剪切和复杂扰动作用下空泡演化过程的认识，可应用于超高速水下航行器流动外形/动力系统一体化设计，对提高航行体减阻率和航行稳定性具有重要意义。