An experimental study to investigate various features of subsurface vortices and their evolutions inside a closed pump intake under different pressure conditions at free surface, and to analyze the influence of a pipe bell with different mean axial velocities at the same water level on flow patterns is presented. For all cases, three different flow regimes are closely observed: various side-wall attached, back-wall attached and submerged vortices structures, and their evolutions are subject to the free-surface pressure for a critical flow rate, the number and strength of all these vortex rise as the absolute value of the pressure increases for a higher flow rate, for a lower flow rate, whether the side-wall vortices occur or not is related closely to the pressure magnitude, and there are no vortices for lower absolute pressure values, the number and the strength of the side-wall vortices increase as the absolute pressure values increase. Besides, based on statistical analyses, the side-wall vortex probability on the right side along the stream-wise direction is much higher than that on the opposite side for all operation cases, particularly single vortex probability, and the back-wall vortex probabilities are quite higher with values of more than 90%, meanwhile, the multi-vortices probability is much higher than that of the single-vortex. The captured vortices have been qualitatively classified into different “vortex zones”: no vortex zones and vortex zones including transition, single- and multi-vortex. The Reynolds number and the absolute value pressure are the most important parameters which influence the existence and the number of these vortices, and the increase of the two parameters reduces the no vortex transition zone and causes bigger difference in the back-wall and side-wall vortex zones.

进行了一项实验研究，研究了在自由表面上不同压力条件下，封闭的泵入口内地下涡旋的各种特征及其演变，并分析了在相同水位下具有不同平均轴向速度的管道钟对流型的影响。 。对于所有情况，都密切观察了三种不同的流动状态：各种侧壁附着，后壁附着和淹没涡结构，其演化受临界流量，自由流体的数量和强度的自由表面压力的影响。这些涡旋随着压力的绝对值增加而增大，对于更高的流速，对于更低的流速，是否发生侧壁涡旋与压力大小密切相关，并且对于更低的绝对压力值不存在涡旋，侧壁涡旋的数量和强度随着绝对压力值的增加而增加。此外，基于统计分析，在所有操作情况下，沿流向右侧的侧壁涡旋概率要比相对侧的概率高得多，尤其是单个旋涡概率，而后壁旋涡概率为值大于90％的情况下，该值要高得多，同时，多涡旋的概率要比单涡旋的概率高得多。定性地将捕获的涡旋分为不同的“涡旋区”：没有涡旋区和包括过渡，单涡旋和多涡旋的涡旋区。雷诺数和绝对值压力是影响这些涡旋的存在和数量的最重要参数，