中文摘要：

采用3D-PIV激光流速仪对立式轴流泵喇叭管和进水池内部流动进行了测量,2个典型流量工况下的测量结果表明：设计流量（Q0）工况时,叶轮进口断面流速场呈对称分布,断面轴向流速均匀度达到0.87,无旋涡发生,喇叭管内及泵叶轮进口水流流态良好;大流量（1.2Q0）工况时,叶轮进口断面流速场呈非对称分布,断面轴向流速均匀度仅0.70,流道及喇叭管内有较强的旋涡产生,并进入叶轮诱发振动。分析了旋涡核心区的细部流动结构,导出了旋涡的数字形态,揭示了涡核内水流圆周分速度的分布规律,涡核中心的流速接近为零,圆周分速随涡核半径增加而增大,在半径3~5 mm范围内速度梯度最大,旋涡的强迫涡特征十分明显。提出了基于流量的单元面积加权流速均匀度及相应的计算公式,使过流断面流速均匀度的计算结果更为合理、更加符合实际。

英文摘要：

Due to less study on the flow field measurements, especially on the three dimensional flow field measurements, only the calculation results of very limited flow field are validated, therefore the further detail experimental study is necessary. The 3D-PIV particle image velocimetry was applied to measure the flow fields inside pump structure, including a vertical axial-flow pump bell-tube and suction passage. The measurement results under two typical operational conditions of flow rate showed that at the operation condition of design flow rate （ Q0 ） , the velocity-field distribution in the impeller inlet section was symmetrical, the axial velocity uniformity of the section was 0. 87, and vortex was not occurred, the flow regime in the bell-tube and the impeller inlet was good. The distribution of the velocity field in the impeller inlet-section at large flow rate （ 1.2Q0 ） was asymmetric, and the axial velocity uniformity of the section was only 0. 70. A pair of strong vortices were formed at each section in both the bell-tube and the space below the bell mouth, which finally entered the impeller and induced vibration. By analyzing the detailed flow structure of vortex core zone, the distribution regularity of circular velocity components in the vortex core was revealed, which were close to zero at the center of the vortex core and increased with the increase of vortex core radius. In the radius range of 3 - 5 mm, the velocity gradient was the largest and the characteristics of forced-vortex of the vortices were evident. A unit area weighted velocity uniformity and the corresponding calculation formulas of the velocity uniformity in flow section were proposed, and the calculated result by the formulas was more reasonable and practical.