蒸汽喷射器内激波与非平衡相变耦合作用机制研究

In this project, the research of coupling effect mechanism of shock and non-equilibrium phase change inside the steam ejector is accomplished, based on a novel approach combining experimental observation and numerical simulation. In the research, with the condensation shock, aerodynamic shock and the non-equilibrium phase change of steam as the study object, the coupling effects of the steam non-equilibrium phase change and shock effects are selected as the breakthrough point, and the effects of the absorption/release of the latent heat on the shock wave are the external characteristics, and the flow visualization technology and the comparative observation method are used in the experiment. In the research, the structure and the transient characteristics of the shock wave are captured by the flow visulization technology combining high speed photography and the schlieren technique, and the boundary characteristics and transition mechanism of the jet flow bounding layer are observed by the flow visulization technology combining high speed photography and the PIV(Particle Image Velocimetry) technique. In the numerical simulation, the double fluid model is developed and used to predict the non-equilibrium phase change and the shock effect. Based on the simulation and the experiment, the local/detail characteristics of the jet flow and the shock wave are captured, and the thermodynamics/dynamics characteristics of the coupling effect for the non-equilibrium phase change and the shock are revealed, and the energy transfer mechanism in the shock dissipation is recognized. The performance of the adjustable ejector with a adjustable spindle in the primary nozzle is studied, and the characteristics of the shock wave and non-equilibrium phase change are investigated in the annular nozzle. Based on the research, the effects of adjustable spindle on the non-equilibrium two phase flow, the flow structure and the performance of the ejector are investigated, which will provide theoretical support for the performance analysis and structural optimization of the ejector.

本课题以蒸汽喷射器内凝结激波、气动激波和水蒸气非平衡相变为研究对象，以水蒸气非平衡相变发生时潜热的吸/放产生的能量传递效应对激波特征的影响为切入点，以流场可视化技术为实验佐证，以对比观测法为技术手段，采用实验观测与数值模拟相结合的方式对喷射器内激波与非平衡相变的耦合作用机制进行研究。采用高速摄像与纹影法相结合的流场显示技术观测流场中激波系结构和激波锋面的瞬态特征，以高速摄像与PIV相结合的方式获取射流边界层的边界特征和转捩特性，以双流体模型求解喷射器流场中非平衡相变与激波的耦合作用，捕获喷射流场中射流边界层、阶跃状激波系的局/细部特征，解构激波与非平衡相变相互作用的热/动力学机理，认识激波耗散效应中的能量传递规律。在喷射器工作喷嘴内添加调节锥，开展环形喷嘴内的非平衡相变及激波特征研究，获得调节锥的加入对喷射器流场结构和喷射器性能的影响规律，为喷射器性能分析与结构优化提供理论支持。

以超音速喷射过程中非平衡相变与激波效应及其对喷射器性能影响为核心，解构了非平衡相变与激波的耦合作用机制，以潜热吸/放产生的能量传递效应为切入点，阐明了凝结激波的分区特性、边界效应和尺度效应，探索了非平衡相变、激波效应、卷吸、湍流、分离涡等特殊流动现象发生、发展的热物理过程及其诱发的非平衡能量传递效应对固定、可调式喷射器性能的影响。在对蒸汽喷射过程非平衡两相流及激波效应研究的基础上，采用水蒸汽真实物性模型，以经典成核理论模型（CNT）为基准，耦合了液滴生长模型、构建了蒸汽喷射过程非平衡相变模型，采用Roe-FDS数值格式、K-w-SST湍流模型、大涡模拟等方式捕获了蒸汽喷射器内非平衡相变与激波产生、发展的规律特征，得到了蒸汽喷射器内非平衡相变、激波效应、卷吸混合与湍流流动作用下的两相流动特征，以射流边界层形态、射流混合长度、射流速度为特征参量，解构了喷射器内射流边界层的边界特征和瞬态特征。进一步研究了非平衡相变及激波效应对变结构可调式喷射器性能的影响机理与规律。. 采用CFD数值模拟与气体动力学函数相结合的方法开展了喷射器设计、优化及特性的理论与应用研究。耦合空气、水蒸气真实物性模型，基于集总参数思想，构建了基于压缩比、膨胀比、射流混合长度、喷射系数、极限工作状态点为评价体系的固定、可调式喷射器设计及优化理论。在此基础上，基于饱和参数区、过热参数区、临界工况区、高真空领域喷射器设计与优化的可靠性和鲁棒性分析。探索了喷射器“正反问题”耦合计算方法和PC双边界模式对索科洛夫经典分区设计理论的修正，在海水淡化所处工况下，尝试了小压缩比（Pc/Ps.≤2.5）与大压缩比（Pc/Ps.＞2.5）统一算法模型递归和基于三种极限工作状态的模型修正，探索了喷射器内壅塞现象与出口背压的相干规律。基于射流混合长理论，开展了非平衡相变与激波效应耦合作用机制的非平衡能量传递效应对蒸汽喷射器耦合规律研究，探索了其与传统气体动力学理论和热力学理论的集成分析方法，为国家科技支撑计划“海洋平台核能海水淡化技术及示范应用研究”提供了技术支持。为神华宁煤国产十万空分装置配套用汽轮机新型卸载调节汽阀设计开发中的“等面积-等流量法”的校核提供了学术启迪，为今后大型工业汽轮机的蒸汽调节阀的设计提供了一定思路。