摘要
为研究0.8Qopt工况下,叶轮及导叶进出口的流场分布情况,选择比转速ns=700的轴流泵进行模型缩放,并对其进行结构改造,以得到能够适合于2D-PIV内部流场测试的试验台。结构改造包括:采用透明的有机玻璃材料代替传统金属材料,达到内部可视化的目的;将传统的锥形扩散式导叶体设计成圆柱状,以减小光学折射的复杂程度;合并转轮室及导叶外筒壁,使之成为一个整体,以消除叶轮区域与导叶区域之间法兰对内部流场的遮挡;将导叶内轴承后移,并加装筋板,使得载荷能够顺利传递到基础中。综合以上手段,成功改造了试验泵段。在PIV试验过程中,利用轴编码器及同步装置,取得了很好的同步效果。同时,以有机玻璃空心球作为示踪粒子,配合新的标定方式,取得了理想的试验效果。从试验结果分析可知:在0.8Qopt流量下,叶轮进口边外缘处受叶顶泄漏影响,使得该处来流向轮毂侧偏转,但叶轮进口前端截面上的流场整体分布较为均匀;叶轮轮毂与导叶轮毂之间存在的顺时针方向漩涡,对叶轮出口边根部附近的流场造成较大的影响,且叶轮出口边与导叶进口边轴向间隙内的流场具有整体向外缘偏转的趋势;导叶出口以后的流线方向则向轮毂侧偏转,且在出口边外缘处出现局部高速区域。
To investigate the flow field distribution at the regions of the impeller and guide vane inlet and outlet under condition of 0.8Qopt, the axial flow pump with ns =700 was selected for model scaling and structural modification, from which we could get a test bed suitable for a 2D-PIV internal flow field test. Structural modifications included： the conventional metal material was replaced with transparent organic glass material to achieve the purpose of internal visualization; the conventional conical diffuser vane was designed into cylindrical shape to reduce the complexity of optical refraction; the runner chamber was merged with a guide vane casing to form as a whole to eliminate the occlusion of the flange to an internal flow field between the region of impeller and diffuser vane; the bearing within the diffuser vane was moved backward and rib plates were installed to make the load transfer to foundation smoothly. Based on the above methods, an experiment pump section was modified successfully, and the efficiency of the experimental pump reached 73.79%, which was close to that of the prototype pump. It was indicated that less damage occurred to the original flow field with structural modification. During the PIV measurement, the shaft encoder and synchronizer were used for better synchronous effect. Meanwhile, an ideal experimental result was obtained by using organic glass hollow spheres as tracer particles, and a new calibration method. As shown in the original PIV images, the particle distribution was homogeneous with most particles appearing to be micro-exposure, which meant an ideal experiment effect. From the analysis of the experimental result, it was indicated that, owing to the effect of the tip leakage flow at the 0.8Qopt operating point, the inflow at the rim of an impeller leading edge deflects to the hub side, but the whole flow field is evenly distributed on the front section of an impeller; a clockwise vortex with an outer diameter larger than the hub between the hubs of an impeller and the guide vane causes a great impact on the flow field near the root of the impeller＇s trailing edge, and the flow field in the axial clearance of the impeller trailing edge and the guide vane leading edge tends to deflect to the outer rim integrally; the streamline direction after the guide vane outlet shifts towards the hub side, which leads to a local high-speed zone at the rim of trailing edge. Moveover, the velocity of the high-speed zone is about double as much as the average velocity of the flow field downstream from the guide vane.
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2013年第23期93-98,F0004,共7页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家自然科学基金(51079063)
国家自然科学基金(51109093)
江苏省博士创新基金
关键词
流场
泵
试验
轴流泵
小流量
泵段改造
PIV
叶顶泄漏
轴向漩涡
flow field
pumps
experiment
axial flow pump
low flow condition
transformation of pump section
PIV
tip leakage
axial vortex
作者简介
作者简介：张华（1988-），男，江苏南京人，博士生，主要从事流体机械及工程研究。镇江江苏大学流体机械工程技术研究中心，212013。Email：zhh091088@126．com
通信作者：施卫东（1964-），男，江苏南通人，研究员，博士生导师，主要从事流体机械及流动特性研究。镇江江苏大学流体机械工程技术研究中心，212013。Emaihwdsh@lujs．edu．cn
