【作者】 杨敬江；

【导师】 关醒凡；

【作者基本信息】 江苏大学 ， 流体机械及工程， 2008， 博士

【摘要】 南水北调等大型水利工程需要大量效率高、运行稳定的轴流泵,而优秀的轴流泵水力模型是保证实型泵(真机)的能量指标、汽蚀指标和稳定运行的基础。水力设计实践表明,采用传统的设计方法设计的水力模型,其性能指标难以满足使用要求。本文采用理论分析、试验研究和数值模拟相结合的方法,采用流线法设计制造了高性能指标的轴流泵水力模型,并已在南水北调东线工程等大型水利工程泵站中得到应用。主要研究工作和创造性成果有:(1)研究确定了轴流泵水力模型系列的参数。为了方便选择泵型,采用保持轴流泵模型的流量不变,通过改变模型设计扬程以改变比转速的方法,得到轴流泵水力模型系列参数,用于设计不同比转速的水力模型。模型泵的流量为0.35m~3/s,扬程范围为2.5～11.0 m,比转速为500～1500。(2)系统研究了流线法设计轴流泵叶轮的方法。提出了一种从叶轮叶片外缘到轮毂线性修正环量分布的方法,加大叶片外缘侧翼型的环量,减小轮毂侧翼型的环量,在轮毂和轮缘之间的翼型的环量修正系数按线性规律变化。提出了叶轮叶片进口冲角从轮毂到轮缘增加的方法,进一步降低叶轮叶片的扭曲,冲角值选取范围为0°～3°,随比转速增加,冲角减小。(3)探讨了适合于轴流泵内部三维定常流动的数值计算方法。以比转速为1000的轴流泵水力模型为算例,并以天津同台测试的试验数据为参照,进行了全流场三维定常数值计算。数值计算采用Reynolds时均N-S方程,标准κ-ε紊流模型,二阶精度差分格式和SIMPLEC算法。CFD计算的曲线与试验曲线的趋势基本一致,最优工况点计算扬程相对试验扬程的最大误差为2.52%,误差绝对值的平均值为4.5%。分析了轴流泵叶轮和导叶表面的速度矢量图、压力等值线图。叶轮和导叶叶片工作面和背面的速度、压力分布有着明显的规律,叶片工作面的相对速度分布比较均匀,基本上按圆柱面分布,自轮毂向轮缘相对速度逐渐增加,导叶工作面的速度基本上沿轴向流出。靠近叶轮叶片轮毂处,沿叶片长度方向压力变化较大,而靠近叶轮叶片轮缘处,沿叶片长度方向压力变化平稳,轮缘处的最高压力及平均压力均高于轮毂处的压力,叶片背面的最低压力点在距头部约25%处。叶轮出口速度环量沿半径方向自轮毂向轮缘逐渐增加,这与水力设计时对叶轮出口圆周分速度进行修正的结果一致。(4)总结了轴流泵水力模型设计中关键参数的选择规律。包括叶轮的叶栅稠密度、轮毂比、叶片数和翼型加厚规律,导叶的叶片数以及与叶轮的轴向间距。本文所取得的研究成果为轴流泵水力设计方法的深入研究提供了借鉴,所开发的轴流泵水力模型的设计质量和准确性得到了进一步提高,降低了新模型的研发成本,提高了泵站工程中原型泵的效率,既具有较高的学术价值,又对南水北调等重大工程具有重要的应用价值。更多还原

【Abstract】 Large scale water conservancy projects such as South to North Water Transfer Project need many higher efficiency and steady operating axial flow pumps. Axial flow pump model with excellent performance characteristics can guarantee the energy and cavitation performance and steady operating of prototype axial flow pump. On the basis of hydraulic design practice, performance characteristics of the axial flow pump hydraulic model designed with traditional design methods can not meet the performance demand.The streamline design method is systematically studied and applied to design of axial flow pump models by theorectical analysis, experiments and numerical simulation. These axial flow pump hydraulic models have been adoped in many pump stations.The main work and the achievements are as follows:(1) A method of constant flow rate and altering head is proposed to determine the parameters of the axial flow pump hydraulic model series with different specific speed for convenient pump models selection. The flow rate of axial flow pump model is 0.35 m~3/s , the head is between 2.5～11.0 m, and the specific speed is between 500～1500.(2) The streamline design method for design axial flow pump impeller has been systematically studied. A method of circulation distribution amendment has been put forward by increasing blade section circulation from hub to tip of impeller.The amendment coefficient of the blade sections between hub and tip circulation is increased linearly.A method has been put forward by increasing incidence angle of impeller inlet from hub to tip for further lowering distortion of impeller blades. Incidence angle becomes smaller with higher specific speed, range of which is from 0°to 3°.(3) Suitable numerical simulation methods for three dimentional steady flow of axial flow pump has been studied. A specific speed 1000 axial flow pump model is simulated based on Reynolds-averaged N-S equations, standard k-εturbulence model, SIMPLEC algorithm and unstructured mesh by FLUENT code.The performance characteristics curves of computation is consistent with the one of experiments.In optimum operating condition, the maximum variation of computational head compared with experimental one is 2.52%, and averaged absolute variation is 4.5%. From computational results, velocity and pressure of impeller and guide vane blade surfaces vary regularly. Relative velocity vectors of impeller pressure surfaces are well distributed in nearly cylindrical surface and relative velocity value increasing from hub to tip. Velocity direction of guide vane pressure surfaces is axial. Near impeller hub, static pressure difference varied wildly along blade chord length, while near impeller tip static pressure difference varied gently. Maximum static pressure and average static pressure near impeller tip are higher than near hub. Minimum static pressure of suction surface is near 25% apart from impeller inlet. Impeller exit circulation increases from hub to tip along radial direction, in accord with linear circulation distribution amendment during hydraulic model design.(4) New key parameters selecting laws for axial flow pump design have been proposed, including cascade solidity, hub to tip ratio, blade numbers, foil section thickness of impeller, guide vanes number ,and the axial distance between impeller and guide vane.This study has provided new ideas for the research on the hydraulic model design method of axial flow pump. The developed hydraulic models have good design quality and accuracy, reduce the cost of developmentd and improve prototype pump performance in pump stations. It is of great academic values, and of great significance to water conservancy projects such as South to North Water Transfer Project.更多还原