低过冷流场中蒸汽-水直接接触冷凝界面现象多场耦合研究

Bubbling deaeration method has been widely applied in the marine steam power system (MSPS), steam direct contact condensation (SDCC) in low sub-cooled water is the hermodynamic foundation of this technology. The flow, heat transfer and acoustic characteristics are three critical factors which play important roles for MSPS’s deoxygenation efficiency and acoustic stealth. For SDCC in low sub-cooled water, the jet cavity occupies larger space and becomes more unsteady due to the relatively low condensation driving potential, posing great challenges for the design and optimization of deaerators. Traditional studies usually focus on certain macro feature of the SDCC phenomenon. The intrinsic correlation between multi-physical fields and the interfacial phenomenon still is lack of complete understanding. The meso-scale interfacial phenomenon, such as the bubble breakage, coalescence, deformation and collapse, turns to be the bottleneck for SDCC study. In this project, based on the analysis of vapor plume characteristics and noise spectrum feature, the multi-physical fields among heat, flow and sound are analyzed deeply, the flow patterm map for SDCC in low sub-cooled water would be constructed considering both vapor plume behavior and acoustic characteristics. Then, the regulation and balance mechanisms between steam injection and vapor condensation are discussed; appropriate bubble growth, breakage, coalescence, and collapse kernels for SDCC process can be established to track the phase interfaces evolutions. the CFD-PBM method would be introduced to investigate the flow field and predict the bubble size distribution for SDCC process. On this basis, the quantitative relationship among noise, vapor plume state, and bubble interface evaluation can be constructed; the noise control theory and methods would be developed for SDCC in low sub-cooled water. This project aims to provide theoretical foundation for promoting SDCC noise control, which can be applid in MSPS and other engineering fields.

低过冷流场中蒸汽-水直接接触冷凝是舰船蒸汽动力系统鼓泡除氧的热力基础，该过程涉及强湍流、相变、多相流等复杂行为，其流动、换热与声学特性是决定系统除氧深度与声隐身性能的重要因素。由于流场过冷度低，蒸汽凝结势小，汽液界面动态演化决定了流场域内热、流、声多场耦合特性，这也是目前的研究重点和难点。本项目通过分析低过冷流场中蒸汽-水直接接触冷凝过程的汽羽形态及界面演化行为，探讨流场中热、流、声多场耦合机制；结合噪声频谱特征分析，建立包含上述综合信息的两相流型图；分析蒸汽喷注与蒸汽冷凝的动态调控及平衡，构建合适的汽泡生长、破碎、聚并和溃灭核函数，耦合群体平衡模型和多相流体动力学模型，预测汽泡尺寸的时空非均匀分布。进而，探索辐射噪声与汽羽形态及界面演化的内在关联，提出相应的噪声控制方法，实现流动、换热与声学特性的同步提升，为其在舰船蒸汽动力系统等领域的应用提供科学指导。

本项目以指导舰船蒸汽动力系统高效低噪声热力除氧为应用目标，围绕低过冷流场中蒸汽-水直接接触冷凝过程热力学、动力学与声学特性开展深入研究，这是一个典型的多物理场、多尺度复杂问题。由于流场过冷度低，蒸汽凝结势弱，射流汽羽影响范围广，汽液界面动态演化决定了相间传热传质、动量传递及辐射噪声特性。深入理解蒸汽喷注和蒸汽冷凝两种控制机制的协调，揭示汽羽界面的动态演化过程及其声学关联，是指导开展相关噪声控制理论与控制措施的基础，具有重要的科学意义和应用价值。.设计并搭建低过冷流场中蒸汽-水直接接触冷凝试验系统，结合流场可视化分析和水声信号处理方法，获得蒸汽水下喷注过程两相汽羽动态演化图像和动态冷凝换热系数；基于双流体模型和双阻力相变模型，实现对低过冷流场中蒸汽-水直接接触冷凝过程的模拟，解决高速射流、相界面演化、蒸汽冷凝伴随的传热传质等难点；通过对低过冷流场中蒸汽-水直接接触冷凝过程流场细节和声学特征之间的关联分析，揭示辐射噪声的产生机理和声学特性，指导提出相应的噪声控制方法和方案，为开展相关声学优化设计提供科学依据。.本项目共发表学术论文15篇，其中国际期刊论文1篇（SCI源刊），国际会议论文10篇，国内期刊论文2篇（EI源刊），国内会议论文2篇。申请国家发明专利共7项，其中授权3项。参加国际学术会议6人次，参加国内学术会议2人次。人才培养方面，3人由助理研究员晋升为副研究员，培养毕业硕士研究生2名。