叶片泵内气液两相流型基础问题研究

Due to the rotation of the impeller and the shear motion between the rotor and the stator, the flow pattern in a vane pump handling gas-liquid two-phase flow will be much more complicated than that in pipe flow. To improve the hydraulic and structure design of a vane pump, the fundamental study on the gas-liquid flow pattern must be strengthened. In this project, through the experiments of two-phase flow observation in working conditions of different flow rates, different rotational speeds and different inlet gas void fractions, the basic characteristics about gas-liquid two-phase flow patterns in vane pumps will be acquired, and the flow pattern classifying means for gas-liquid two-phase flow in vane pumps will be presented. Based on the flow observation and the bubble dynamics theory, the phase interaction model in different flow patterns will be studied; by analyzing the influences of flow pattern, rotation and gas void fraction on turbulence scale and boundary layer, a new method of hybrid turbulence model will be developed. For the cases of compound flow pattern and pattern transition, the flow pattern identification method will be presented from the numerical point of view, and the stable numerical solving technology will be studied. Based on the above study, the corresponding numerical modules will be developed and the gas-liquid two-phase flow will be simulated in the high performance cluster system. The flow characteristics and the dominant factors will be analyzed, and the formation and transition mechanism of the flow patterns will be explored, as well as the connections between the flow pattern, the flow characteristics and the pump performances.

由于叶轮的旋转作用和动静叶轮间的剪切效应，叶片泵内气液两相流动具有比管道流动更加复杂的流动型态，加强对泵内流型相关的基础问题研究有助于系统而有针对性地改进叶片泵的设计。申请者通过不同流量、不同转速和不同进口含气率的系列工况流动观测实验，认识泵内气液两相流动的基本特征，提出针对叶片泵的气液两相流型划分方法；以流动观测结果和气泡动力学理论为基础，研究不同流型条件下的气液相间作用模式；通过分析流型、旋转效应和含气率等因素对湍流尺度和边界层的影响，发展新的混合湍流模型方法。为了适应流型转捩和复合流型的情况，从数值角度提出泵内流型的识别方法，研究该复杂情况下的稳定求解技术。在此基础上，开发相应的程序模块，在高性能并行计算系统上对泵内气液两相流动进行精细的数值计算，分析不同流型条件下叶片泵内气液两相流动的基本规律及其受控因素，总结流型形成和转捩的物理机制，探索流型与泵内流动规律及泵性能特性的基本联系。

由于叶轮的旋转作用和动静叶轮间的剪切效应，叶片泵内气液两相流动具有比管道流动更加复杂的流动型态，加强对泵内流型相关的基础问题研究有助于系统而有针对性地改进叶片泵的设计。该项目通过不同流量、不同转速和不同进口含气率的系列工况流动观测实验，增强了人们对泵内气液两相流动基本特征的认识，提出了针对叶片泵的气液两相流型划分方法；以流动观测结果和气泡动力学理论为基础，研究不同流型条件下的气液相间作用模式，并对包括叶轮和导叶的泵全流道进行了广泛的相间作用量级分析；通过分析流型、旋转效应和含气率等因素对湍流尺度和边界层的影响，发展了适应于泵内复杂流型情况的湍流封闭模型。为了适应流型转捩和复合流型的情况，从数值角度提出泵内流型的识别方法；从时间推进方法，松弛方法和格式转换方法等方面研究了复杂工况下的稳定求解技术；基于CEL语言实现了相间作用模型、湍流模型、非均匀气泡模型等在计算软件中的嵌入。在此基础上，通过高性能计算系统对泵内气液两相流动进行精细的数值计算，分析不同流型条件下叶片泵内气液两相流动的基本规律及其受控因素，总结了流型形成和转捩的物理机制，探索了流型与泵内流动规律及泵性能特性的基本联系。此外，还对介质属性（包括介质粘性及非牛顿特性）对泵内气液两相流动的影响规律进行了分析。该项目研究内容及成果丰富了叶片泵内气液两相流动理论，为高性能气液混输泵的设计开发提供了理论参考。