变温多相流场金属过流壁面冲蚀/空蚀耦合损伤机理研究

The localized corrosion problem caused by multiphase flow of oil, gas and sand in the transportation process of deep sea oil and gas gathering pipeline will cause wall thinning or perforation leakage, which is important cause of the accident in the offshore oil platform. The key to solve this problem is to clarify the coupling damage mechanism of the flow-through metal wall erosion / cavitation erosion in the variable temperature multiphase flow..Construct the model based on Lattice Boltzmann Method - Discrete Element Method (LBM-DEM), analyzing the couple relation between cavitation bubble and particles motion in the multiphase flow, to quantify the mechanism and key parameters of the interaction between particles and particles near the metal wall. Conduct experiments to discover the near-metal-wall cavitation collapse details under ultrasound irradiation, jet impact effect and the particle motion feature during the cavitation collapse process. Simulate the variable temperature multiphase flow circumstance to develop the closed pipeline erosion/cavitation erosion experiments, then modeling of microstructure characterization of metal wall damage. The physical difference between erosion and cavitation and coupling damage is studied. A prediction criterion for local corrosion of flow-through metal wall, at variable temperature and multiphase flow field is put forward, which establish the foundation for optimizing the structure of pipeline and optimizing the layout of in-service inspection..The research results have practical significance for corrosion protection, safety assessment and life prediction technology of sand containing multiphase flow in the field of oil and gas gathering and transportation pipeline, as well as irrigation works, chemical industry, ship engineering and other fields.

深海油气集输管线介质输送过程中油、气、砂多相流动引起的局部腐蚀会导致壁面减薄或穿孔泄漏，是导致海洋石油平台事故的重要原因。实现变温多相流动中金属过流壁面冲蚀/空蚀耦合作用蚀损预测与控制是解决此问题的关键。.项目通过构建多相流中空泡与颗粒运动耦合的格子Boltzmann-离散单元法（LBM-DEM）模型，理清近金属壁面空泡与颗粒相互作用的机制与关键参数；研究金属壁面附近的空泡在超声作用下的溃灭特性、射流冲击作用及空泡溃灭过程中的颗粒运动特性，模拟变温多相流动条件开展封闭式管道循环冲蚀/空蚀试验，建立金属壁面损伤微观形貌表征模型；研究抗冲蚀/空蚀及耦合损伤性能的物理差异，提出变温多相流场金属过流壁面局部腐蚀预测准则，奠定集输管线的结构优化和在役检验布点优化的应用基础。.研究成果对油气集输管线以及水利、化工、船舶等领域中含砂多相流金属过流壁面的腐蚀防护、安全评定、寿命预测等技术具有现实意义。

油气输运管线输送过程中油、气、砂多相流动引起的局部腐蚀会导致壁面减薄或穿孔泄漏，是导致油气管线漏损的重要原因。. 项目通过构建多相流中空泡与颗粒运动耦合的模型，理清近金属壁面空泡与颗粒相互作用的机制与关键参数。通过模型建立和数值求解器的定制，数值模拟了远场中蒸汽泡的溃灭、近壁面蒸汽泡的溃灭以及远场中固定颗粒和空泡的相互作用，模拟结果与实验结果符合性较好。研究了单个蒸汽泡溃灭时的能量变化以及相应流场分析，建立了考虑热动力学和相变影响的求解器，模拟近金属固壁附近的空泡溃灭，较好地再现了气泡前两个周期的基本物理特征，准确地捕捉了空泡形态、温度以及相应地压强和速度的瞬态过程，与实验结果吻合较好。数值模拟自由流场中空泡的溃灭过程，在空泡的内能守恒中，考虑了质量输运、热传导以及压强做功等各因素，揭示了空泡在溃灭过程中的能量守恒和转化机制。数值模拟变温多相流动条件冲蚀/空蚀耦合作用，提出变温多相流场金属过流壁面局部腐蚀预测准则和在役检验布点优化方法。. 研究成果对油气输运管线、埋地管线以及水利、化工等领域中含砂多相流金属过流壁面的腐蚀防护、安全评定、寿命预测等技术具有一定的现实意义。