空化热流体动力特性与机理研究

Cavitating flow, characterized by the phase change process, is a kind of thermo-fluid flow phenomenon. It is of critical importance to investigate the energy, mass and momentum transfers, and their interactions with each other. Development in the theory and research method of the cavitating thermo-fluid flows greatly contributes to the research of cavitation, as well as the advanced technology in the fields of energy, environment, aerospace, superconduction and issues related to national economy. Based on the plenty of research experience and sophisticated facilities in experiment and calculation, the experimental methods and theoretical analysis on the cavitating thermo-fluid flows are improved. The multi-field synchronization measurements, combined with the numerical simulation methods considering the thermal effects, are applied to investigate the flow structures under different conditions. The characteristics and physical mechanism of the momentum transfer process in such thermo-sensitive fluid flows are investigated, and the turbulent flow structures and characteristics in different cavitation stages are also studied. Meanwhile, the thermodynamic characteristics in each cavitation stage and the influences of energy transfer on mass transfer process are revealed. The evolution of the cavity and the wall pressure variation are performed to demonstrate the mechanism and hydrodynamic characteristics of cavitating thermo-fluid flows.

以相变过程为特征的空化流动是一种热流体流动现象，研究流动过程中的能量传输、质量传输和动量传输及其相互作用是把握空化流动本质的关键。发展空化热流动的理论与方法不仅是学科发展的内在必然，同时也关系到能源、环境、航天和超导等高新技术和国民经济等重要领域的关键技术问题的解决。申请者基于已有的研究基础和具备的实验与计算条件，发展空化热流体动力学的实验技术与理论分析方法；综合应用多场同步测量技术和考虑热力学过程的空化流动数值计算方法，研究不同空化条件下的流场分布，揭示在包含质量传输和能量传输过程的流动中动量传输特性及其形成机理，掌握热力学敏感介质不同空化阶段湍流流场结构与特征；研究空化的发展过程，揭示空化流动过程能量传输对于质量传输的影响机理，掌握不同阶段空化的热流动特性；研究热力学敏感介质中空穴的非定常演化过程，和对应的压力场变化，揭示空化热流体动力的形成机理，掌握空化热流体动力特性及其变化规律。

经过4年的研究工作，申请者团队搭建了国内首套大范围温度变化条件下的热流体空化流动测试平台，发展了空化热流体动力学的实验技术与理论分析方法，获得了液氮在大范围温度变化条件下的空化特征和随温转捩特性，揭示了流动参数和物质属性对热流体空化流动的综合作用机制。建立了一套完整的热流体空化流动数值计算方法，综合应用多场同步测量技术和考虑热力学过程的空化流动数值计算方法，研究了不同空化条件下的流场分布，揭示了包含质量传输和能量传输过程的流动中动量传输特性及其形成机理，揭示了热流体空穴内部的流动结构和脱落机制，提出了热流体在不同温度下的空化发展模式和脱落机制。研究了热流体空化的发展过程，揭示了空化流动过程能量传输对于质量传输的影响机理，掌握了不同阶段空化的热流动特性。发展了适用于各类热流体空化随温转捩的判据，该判据对于工程中避免热流体空化造成的影响具有重要的指导意义。