多级导叶式离心泵的内部流动及能量性能预测

【作者】 张学静；

【导师】 杨军虎；

【作者基本信息】 兰州理工大学 ， 流体机械及工程， 2004， 硕士

【摘要】 在水力机械能量特性的研究中，计算机辅助设计工具变得越来越重要。特别是：用计算机辅助生成的流体动力学的计算结果(Computational Fluid Dynamic(CFD))越来越多地被水泵研究者所使用。一方面可以节省实验的资源，缩短新产品的研制时间；另一方面它可以显示不能从实验工具中得出的流动特性的细节。因此，该研究具有重要的理论及经济意义。 本文所作的主要工作有：首先利用Fluent前处理软件Gambit对MD40-6.3多级清水离心泵的叶轮与导叶进行建模，生成网格。接着，对模型进行了物理特性、边界条件及初使条件的定义，对流场进行了计算。然后，改变工况对流场重新进行模拟。最后，根据计算的数据预测了该多级清水离心泵一级的能量特性曲线，并与实验数据进行了比较。 本文的主要研究成果有：1、如何利用Gambit对离心泵叶轮与导叶进行三维造型以及建立三维实体模型时的一些成功做法。如：对建模的总体规划与具体规划采用何种模型，实体与虚体如何选择，网格生成技术与灯光煊染如何应用等。2、利用Fluent6.0软件对MD40-6.3多级泵的叶轮与导叶内部流场进行模拟，经数值模拟发现：(1)在小流量工况及设计参数工况下叶轮的进口附近有回流，这说明该多级泵的第一级叶轮采用了加大流量设计法。(2)叶轮出口附近存在一与叶轮旋转方向相反的二次流动特征，即轴向旋涡，但轴向旋涡在小流量工况及设计工况下较大，而在大流量工况下较小，轴向旋涡不明显，这和传统理论认为由于叶片有限(此时才有轴向旋涡)引起滑移量和工况无关不吻合，这一现象还需进一步深入研究。(3)由导叶的流场分布可以看出，从叶轮中收集到的液体实现了由速度能向压力能的转变，即速度流经扩散段逐渐减小，压力逐渐增大的变化趋势。但从反导叶出口的速度值可以看出此反导叶出口的速度不合适，并且在压力图上可以看到在出口区产生了一个低压区，应改变型线、轴向宽度或叶片厚度变化规律。3、预测了该多级泵一级的能量特性曲线。结果表明：在设计工况附近，预测值与实验值吻合较好，在其它工况点，特别是小流量工况点，误差较大。更多还原

【Abstract】 In the R&D of hydraulic machinery computer-aided design tools become increasingly important to support the machine design and performance prediction. In particular, Computational Fluid Dynamics (CFD)are more and more used by pump manufacturers. On one hand it is applied in order to save experimental resources and shorten the period of exploitation for new productions, on the other hand it is able to show detailed flow features, which are not assessable by experimental tools,so the research is very significant in theory and economy.In the paper,at first, three-dimensinal modeling and meshing of the impeller and vaned diffuser through a centrifugal pump stage have been performed .and then Steady state computations of the flow in many working conditions have been done and the pressure and velocity distribution in multistage pump are obtained,so some opinions is given for improvementat last,we can get the performance curve,such as H-Q curve and -Q curve by collecting the data.The main research production of the thesis is as follows: 1 , Some experiences are acquired about how to design the model and how to select the real object or virtual object and how to use meshing and lighting technics by modeling the impeller and vaned difruser.2, The pressure and velocity distribution in components of multistage pump such as inlet , outlet N blade , hub , cashing, meridional , spanwise. positive diffuser, diffusing and reversing diffuser are obtained: 1) There is reverse flow in inlet of impeller in the low and design working conditions that shows the method of increasing flux is taken.2)Circumfluence is observed outlet .That it is great in low and design working conditions is conflict with the traditional theory which considers the circumfluence is independent of the working conditions.3) Some opinions is given for improvement of designing the reverse diffuser such as redesigning the linetype,the width along with the axis or the thickness of blades and so on.3, We get the performance curve through a centrifugal pump stage by calculating.The comparison of the prediction with the experiment shows that the errors are low comparing with the experimental data at design condition,but the errors are high at other working conditions especially at low flux.更多还原