叶轮出口后加装双层流道结构的轴流泵外特性研究  

Influence of Double-layer Flow Passage Structure after Impeller on External Characteristics of Axial-flow Pump

作　　者：周勇胜 陈斌 张德胜[3] 张华 杨陈 ZHOU Yongsheng;CHEN Bin;ZHANG Desheng;ZHANG Hua;YANG Chen(School of Mechanical Engineering,Hefei University of Technology,Hefei 230009,China;School of Environmental Science and Engineering,Nanjing University of Information Science and Technology,Nanjing 210044,China;Research Center of Fluid Machinery Engineering and Technology,Jiangsu University,Zhenjiang 212013,China;College of Hydraulic Science and Engineering,Yangzhou University,Yangzhou 225009,China)

机构地区：[1]合肥工业大学机械工程学院,合肥230009 [2]南京信息工程大学环境科学与工程学院,南京210044 [3]江苏大学流体机械工程技术研究中心,镇江212013 [4]扬州大学水利科学与工程学院,扬州225009

出　　处：《农业机械学报》2022年第2期149-157,176,共10页Transactions of the Chinese Society for Agricultural Machinery

基　　金：国家自然科学基金项目(51776087)。

摘　　要：轴流泵在最优工况流量点的两侧效率下降快,在小流量工况时流量扬程曲线还存在马鞍形的不稳定流量区域。针对此问题为轴流泵设计了一种双层流道结构,此结构在几何上表现为在靠近轮毂侧从紧临叶轮出口边起延伸至后导叶体内增加了一个筒形隔板。以此内筒和导叶轮毂的间距与导叶流道宽度的比值λ作为变量几何参数,研究了不同几何参数对轴流泵外特性及内部流场的影响。研究结果表明:叶轮出口后的双层流道结构能够在不稳定流量区域提高扬程、减小流量扬程曲线的正斜率,扩大安全运行流量范围。在大于设计流量时,双层流道减少了导叶后流道近外壁区域的流动分离,显著提升了扬程。通过对比分析λ为1/3、1/4和1/5时的计算结果,发现双层流道在λ=1/3时扬程提升效果最佳,3种间距的扬程差别在4%以内。The efficiency of axial-flow pump decreases rapidly on both sides of the optimal flow condition,there is a saddle pattern unstable flow range at low flow side.It is of practical significance to study the internal flow field and external characteristics of axial-flow pump under full flow range,and put forward improvement methods to broaden the workable flow range.The relative flow angles at different radial positions varied along the impeller trailing edge.When the flow decreased,the flow surface component of absolute velocity at different radius decreased at the same step,but the circumferential component of absolute velocity varied greatly according to the relative flow angle of their respective velocity triangle,resulting in the difference of head performance at different radii,the flow deflected towards the outer edge of the passage,and a backflow and vortex area at hub side after impeller was formed.This axial-flow model featured a built-in motor inside the flow passage,so the flow out of the guide vane was a diffusion flow.When the flow separation conditions were met,the boundary layer separation would occur on the inner wall of the pipe.The vortex would develop from the boundary layer to affect the movement of the mainstream.Generally,the methods to control flow separation included:controlling the deceleration mode of the mainstream,eliminating the boundary layer by bypass the boundary flow or injection a flow,turning the laminar boundary layer into a turbulent boundary layer,and separating the flow passage and so on.For this model,the approach of adding a separator to form the double-layer flow passage can deal both the difference of the circumferential component of absolute velocity at different radii after impeller and reduce the downstream flow separation.The geometry of this structure was characterized by the addition of an inner conical tube at hub side.The tube started closely from the impeller trailing edge and extended into the guide vane.The ratio of the distance between the tube wall and the guid

关 键 词：轴流泵 双层流道 流动分离 试验 数值计算 

分 类 号：TH312[机械工程—机械制造及自动化]