内压缩混输泵气液单向阀相界面演化及失稳机理研究

Oil-gas pump is the key techonology of conveying crude oil and recovering natural gas at home and abroad. Due to the variable working conditions, it is particularly important to maintain the stability of two-phase flow near the outlet for efficient and long-peroidic transportation and pressurization. This research aims to explore gas-liquid interface’s evolution and instability under the action of outlet valve’s dynamic opening and closing in internal compressed pump. Basic theoretical analysis, experimental research and numerical simulation are used to study two-phase coupled flow field of valve clearance. Primarily, some mature theories such as fluid mechanics, heat transfer theories, and gas-liquid two-phase flow theory are comprehensively utilized to investigate the valve’s real-time movement. The mathmatical models describing valve’s instantaneous opening and closing, suspension and hysteresis characteristics are established, and accordingly theoretical analysis methods of valve’s motion features during the process of exhausting gas-liquid two-phase flow are formed. Furtherly, nonlinear gradient flow field of valve clearance is investigated and gas-liquid coupling and turbulent effects are analyzed. The evolation shape and law of gas-liquid phase interface under transient conditions are revealed, and the migration rules of pressure wave and void fraction wave are discussed. Based on above results, the incentive and control mechanism of phase interface’s instability are explored and the dynamic theory model of gas-liquid interface is finally set up. Furthermore, the interaction mechanism of two-phase coupling flow in valve clearance and valve's movement is revealed, and in terms of gas-liquid flow control, the design method of vertical outlet valve will be explored. The expected results will provide theoretical foundation for development and application of design system of efficient oil-gas transportation equipments.

油气混输泵是实现密闭输运的关键设备，频变工况下保持出口两相过流的稳定性对于混输泵的高效长周期工作尤为重要。本课题旨在研究内压缩混输泵出口单向阀动态启闭作用下气液相界面的动态演化及失稳机理，拟对阀隙内部气液耦合流场开展基础理论分析、实验研究和数值模拟工作。综合利用流体力学、传热学、气液两相流理论等相关知识，建立单向阀瞬时启闭、悬浮及滞后阶跃的数学模型，形成排气排液单向阀运动特性的理论分析方法；研究阀隙非线性梯度场下气液耦合作用及湍流扩散效应，揭示瞬变工况下相界面形为结构及演化规律，分析内压缩—解压缩过程中压力波及空泡份额波的迁移特征；探究阀隙相界面失稳诱因及控制机理，建立单向阀气液相界面动态输运理论模型，构建单向阀启闭运动与阀隙耦合流动的作用机制，并探索基于流动控制的单向阀设计方法。预期成果将为高效油气混输产品设计体系的开发及应用奠定理论基础。

油气混输泵是油气开采过程中长距离密闭输送的核心设备，也是有效增加伴生天然气资源回收、降低空燃污染的重要增压单元。在苛刻或恶劣输运工况下，油气混输泵的过流能力及输送性能面临极大考验，其可靠性与稳定性直接关系着整个混输管路系统能否安全运行。本项目针对内压缩混输泵关键过流部件—单向阀内两相流动稳定性问题，基于流体力学和气液两相流理论建立气液单向阀瞬时启闭数学模型，开展单向阀气液相界面动态演化及失稳机理的研究，分析非稳输运过程泵腔和阀隙气液动力学行为和瞬时湍流特征，揭示单向阀非线性运动与阀隙耦合流动之间的相互作用机制。主要研究成果包括：⑴ 建立了内压缩往复式油气混输泵用气液单向阀运动理论模型，完成了油气混输泵吸排过程单向阀滞后效应的理论分析、模拟仿真及实验验证；⑵ 开展了单向阀PIV流场测试及分层流态下气液相界面演化研究，建立了单向阀气液相界面输运理论模型，揭示了阀隙内部宏微观流动特征、气液相界面动态形为结构及迁移规律；⑶ 研究了“活塞—单向阀”非线性协同作用下内压缩油气混输泵“膨胀—吸入—压缩—排出”的全工作周期，探究了单向阀阶跃运动与阀隙气液耦合流动的相互作用机制，得到了泵腔和阀隙内部两相空泡份额瞬时分配及等值界面非稳变化规律，结合混输泵吸排瞬态脉动揭示了变工况对单向阀吸排不稳定性的影响机制，探索油气混输泵内部气液等值相界面失稳诱因，并尝试设计与优化高效混输泵及其单向阀结构型式。本研究不仅可以完善新型内压缩油气混输技术体系，为气液两相阀设计及分析方法提供理论与技术依据，而且对提高我国油气混输设备的自主研发水平，推动节能技术进步、加速高能耗产业的节能改造方面具有重要的意义。