基于旋转湍流尺度解析与界面追踪的轴流泵站进水池吸气涡形成机理研究

The axial-flow pump station with opening intake usually suffers from the air-entrained vortex, which can make the operation unsteady. This type of vortex is of general concern in the fields of both academy and engineering. Focusing on the unrecovered formation mechanism of air-entrained vortex and the fact that current researches have not sufficiently considered the influence of the pump operating conditions, the project will take the combination of intake, elbow pipe and axial-flow pump as the research object. Based on the SST k-ω-v2 model for rotating turbulence and the FBM method for scale resolving, a new turbulence model adaptive to the air-entrained vortex will be proposed to solve the problems of insufficient numerical stability and resolving ability for vortex of the existing model. The free surface tracking method S-CLSVOF will be applied to capture the interface between air and water, to solve the problem that the interface by VOF is blurred and it is difficult to capture the curvature of the interface. In addition, the filter width selection criterion and the meshing strategy will be explored. The PIV and high-speed photography technics are also combined to obtain the complete flow field. Analysis of the formation mechanism of air-entrained vortex can be done afterwards, and the influence of pump operating condition and geometric parameters of intake and elbow pipe on the air-entrained vortex will be brought to light. The relation between the critical submergence and flow parameters will be constructed. At last, the effective method for suppressing the air-entrained vortex will be proposed. This project can provide a scientific basis for improving the prediction accuracy of the air-entrained vortex and optimizing the design of the intake to ensure the steady operation in axial-flow pump station.

吸气涡易形成于轴流泵站开敞式进水池，危及泵的稳定运行，是水力机械领域普遍关注的学术和工程难题。本项目针对轴流泵站进水池吸气涡形成机理不明确、现有研究未充分考虑泵运行工况影响的问题，以进水池、喇叭管、轴流泵组成的整体为研究对象；基于体现旋转效应的SST k-ω-v2模型与尺度解析的FBM方法建立适于吸气涡模拟的湍流模型，解决现有模型数值稳定性及涡流解析能力不足的问题，在捕捉吸气涡界面时引入S-CLSVOF界面追踪方法，解决VOF方法交界面模糊且难以捕捉交界面曲率的问题，探索网格处理策略与新模型的滤波尺度选取准则；结合PIV与高速摄影获得完整的流场结构，分析吸气涡形成机理，明确轴流泵运行工况与进水池、喇叭管结构参数对吸气涡的影响，建立吸气涡临界淹没深度与流动参数的关系，提出有效的吸气涡抑制措施。本项目可为提升吸气涡的预测精度、优化轴流泵站进水池的设计提供科学依据，保障轴流泵站安全稳定运行。

吸气涡易形成于轴流泵站开敞式进水池，危及泵的稳定运行，是水力机械领域普遍关注的学术和工程难题。本项目以揭示吸气涡形成机理为核心目标，基于模型试验和数值模拟两种研究方法，开展了泵站开敞式进水池内吸气涡的研究。.首先，由于吸气涡具备典型的水气交界面及漩涡特征，其准确解析依赖于湍流模型的精度，根据尺度解析方法VLES的基本思想建立了一种三方程的VLES模型，充分体现了漩涡流场的局部旋转效应，实现了进水池内多尺度湍流的准确解析，提高了吸气涡的捕捉能力，为吸气涡的进一步研究奠定了基础；其次，为进一步提升预测精度并提高计算效率，探索了网格、计算时间与界面追踪方法对吸气涡预测效果的影响，引入新型交界面处理方法S-CLSVOF并验证其在处理吸气涡水气交界面时的优势，同时进一步明确了吸气涡准确模拟所需的网格数量级与所模拟的物理时间，构建了完善的吸气涡数值模拟方法；再者，搭建了可调节的进水池模型试验台，实现了进水池悬空高、后壁距、宽度的调节，研究了不同参数组合下的进水池吸气涡特征，结合数值模拟明确了吸气涡的演化规律，发现了以壁面反射波为主要特征的吸气涡初生阶段，基于涡拟能输运方程揭示了拉伸与倾斜效应在吸气涡形成及运动过程中起到的重要作用，发现了管壁流动分离的非对称特征，阐释了喇叭管位于水池中线时仍产生非对称流动的原因；最后，结合吸气涡演化规律提出了吸气涡抑制措施并验证了其效果。项目研究结果丰富了湍流的解析方法，完善了吸气涡数值模拟方法，加深了对进水池吸气涡的理解，优化了吸气涡抑制手段，为优化进水池设计、保障轴流泵站安全可靠运行提供科学指导。项目的研究成果得到了不同程度的应用。