渣浆泵叶轮磨损的数值模拟及试验

    Numerical simulation and test on impeller wear of slurry pump

    • 摘要: 为研究渣浆泵运行过程中叶轮的磨损情况,该文以一台离心式工程塑料渣浆泵为研究对象,对其全流场进行了结构化网格划分,首先对包括设计工况点在内的5个工况进行了清水条件下的数值模拟,并与试验数据进行对比,发现最大误差不超过5%,设计工况点误差不超过3%,说明所用数值模拟方法得到的结果是可信的。随后基于ANSYS CFX商用软件中的Particle欧拉多相流模型,对模型泵内流场进行了固液两相数值模拟并进行了快速磨损试验,模拟与试验结果表明:叶轮磨损较严重的部位位于叶片进口边、流道中前段靠近叶片压力面的后盖板内侧、叶片压力面与后盖板交界处及叶片压力面端面;背叶片的磨损主要发生在叶片压力面外缘,并由此处开始往轮毂处发展,磨损形状大致呈抛物线型,分析认为隔舌处的高压引起流道中颗粒相回流撞击背叶片外缘是造成背叶片磨损的主要原因。通过模拟结果与试验结果的对比,证明所采用的数值模拟方法可以有效地预测渣浆泵运行时叶轮的磨损,其结果可较好地解释磨损产生的原因,该研究可为今后渣浆泵叶轮抗磨损性能的优化设计提供参考。

       

      Abstract: Abstract: The centrifugal slurry pump is a device that is used to deliver high density fluid containing suspended solid. It is generally used in electricity, mining, metallurgy, transportation, water conservancy and environmental protection industry. In order to study wear characteristics of impellers during slurry pump working, a centrifugal engineering plastic slurry pump was chosen as the main study model. The entire solid-liquid two-phase flow field in the model pump, which includes inlet, impeller, volute, back blade passage, and gap was meshed by structured girds with ICEM CFD software. Firstly, single-phase flow fields under five working conditions, including the design working condition, were simulated with the SST k-ω turbulence model, and the simulative external characteristic curves were compared with test results. It was found that the maximum error is less than 5%, and the error at the design working condition is less than 3%. It showed that the results of simulation are reliable. Based on the results achieved, mentioned above, particle multiphase model in ANSYS CFX software was adopted to simulate the solid-liquid two-phase flow in the model pump. To verify the results of simulation, a wear test rig was set up to study the abrasion of impellers during the operation of pumps. The results of simulation and test showed that: the distribution of volume fraction of solid-phase has a good agreement with the wear pattern of hydraulic components in impellers during the wear test, and the two-phase flow field achieved by simulation can be used to explain the generation of abrasion. The areas with relatively more severe abrasion in impeller passages are located at the inlet edge of blades, the surface of the back shroud near the inlet edge and pressure side, as well as the junction between the pressure side and back shroud which does not extend to the outlet edge, because the existence of low speed circulation at the inlet edge of blades can easily lead to the gathering of solid particles which will aggravate the abrasion of inlet edge. Additionally, the particles that flow into the passages have an axial speed, which make them move towards the back shroud, finally causing the impact, and the flow separation of particles occurs at the pressure side of blade near the outlet edge. The most severe abrasion are in the back blade passages located at the pressure side near the outlet edge of the impeller, and the abrasion pattern develops towards the hub, which leads to a parabolic wear shape. The abrasion at the other areas in the back blade passages can be neglected. The main reason obtained from the analysis which mainly causes the abrasion of back blades was the impact between the particles and the back blades induced by the back flow under the effect of high pressure at the volute tongue. Through the comparison of numerical and test results, the simulation method was proved to be viable in predicting the wear characteristics of impellers during the operation of pump, and the two-phase flow field achieved from simulation can provide some direction and reference information for optimization design.

       

    /

    返回文章
    返回