离心泵内悬移质固液两相流相间作用模型及泥沙磨损特性研究

The part abrasion of centrifugal pump along the Yellow River is a common issue, which harms the normal operation of pumps seriously. Numerical simulation is widely used to study the sediment erosion characteristics of the centrifugal pump. However, the common inter-phase force models of solid-liquid two-phase flow numerical method are obtained according to the specific sediment conditions, so these models are not suitable for calculating the strongly turbulent solid-liquid two-phase flow mainly with suspended sediment in centrifugal pump. For solid-liquid two-phase flow with the suspended sediment, the accuracy of the simulation results calculated by these models is low. The particle movement and particle diffusion are influenced easily by the turbulence flow and the change of flow field. In the study, a new drag force model with the non-linear relationship between relative change ratio of the drag force coefficient and turbulence intensity considered is proposed, meanwhile a new sediment diffusion coefficient model considering the influence of the fluid flow velocity on the turbulence structure is established. These new models are obtained based on the existing experimental data and theoretical achievements. The two type new models as the high-precision calculation model are provided to calculate the solid-liquid two-phase flow field mainly with suspended sediment. The new models are verified according to the experiment investigation about suspended sediment concentration distribution in circular tube, then the new models are applied to study the mechanism about the influence of the second flow size，intensity，movement and evolution on pump erosion characteristics. The sediment erosion rules of centrifugal pump under different operating conditions are also obtained. The final investigation achievements offer scientific guide for centrifugal pump operation.

黄河沿岸的离心泵普遍存在磨损问题，部件的磨损会影响水泵的安全高效运行。数值模拟是研究离心泵泥沙磨损特性的常用方法，但是固液两相流数值方法中常用的相间作用模型都是根据特定的泥沙颗粒条件提出的，并不适合离心泵内以悬移质为主要颗粒且湍动强烈的含沙水的计算，导致计算精度较低，因为悬移质颗粒的运动和扩散更容易受到湍流和流场流态变化的影响。本课题根据现有的试验研究和理论成果，在现有相间作用模型的基础上，发展考虑湍流强度对阻力系数相对改变率非线性影响的阻力模型，并提出考虑流体流速改变对湍流结构影响的泥沙扩散系数模型，为悬移质固液两相流数值计算提供高精度计算模型；通过透明玻璃圆管中悬移质固液两相流浓度测量的试验验证后，将新建模型推广应用于揭示离心泵内部二次流的大小、强度和发展运动对磨损影响的机理，并研究不同运行工况对离心泵泥沙磨损特性影响的规律，为离心泵的安全、高效运行提供科学指导。

黄河沿岸的离心泵普遍存在磨损问题，部件的磨损会影响水泵的安全高效运行。数值模拟是研究离心泵泥沙磨损特性的常用方法，但是固液两相流数值方法中常用的相间作用模型都是根据特定的泥沙颗粒条件提出的，未考虑湍流和流场流态变化对悬移质颗粒运动和扩散的影响，并不适合离心泵内以悬移质为主要颗粒且湍动强烈的含沙水的计算，导致计算精度较低。同时，抽送悬移质小颗粒的离心泵内固液两相流场及磨损特性尚不清楚，导致不能针对性的提出离心泵磨损性能的优化设计方法。本项目首先通过对双流体湍流模型、阻力模型、泥沙扩散系数模型、磨损模型和磨损计算方法的研究，为离心泵内悬移质固液两相流数值计算选择基础计算模型，为深入研究离心泵内悬移质固液两相流数值计算奠定基础。然后，针对悬移质固液两相流，考虑惯性效应和湍动效应对阻力系数的综合影响。根据理论研究和试验数据分析，得到湍流修正函数最终表达式，建立阻力修正模型。最后，通过圆管中悬移质固液两相流的试验验证后，将新建模型推广应用于揭示离心泵内部二次流的大小、强度和发展运动对磨损影响的机理，并研究不同运行工况下离心泵泥沙磨损特性、非定常磨损特性及压力脉动传播特性。同时，基于反问题设计进行了离心泵叶轮的泥沙磨损性能优化研究。本研究为准确计算悬移质固液两相流提供了新的模型，揭示了离心泵内泥沙磨损特性，通过优化设计改善了离心泵泥沙磨损性能，为离心泵与泵站的安全、高效运行提供科学指导。