水轮机在偏离最优工况运行时，水流的环量会使尾水管中心产生低压并形成涡带。
In case of the turbine is operated departing the optimum condition, the low presure and the vortex band will be established in the draft tube centre by the flow circulation.
导出了二维浅水流动的涡动方程与速度环量的随体导数表达式，以此为基础，分析了二维浅水流动中旋涡的动力学性质；
The vorticity equation was first established and the characteristics of vortex motion in two-dimensional shallow-water flows was analyzed, and then discrete vortex method (DVM) was briefly described.
导出了二维浅水流动的涡动方程与速度环量的随体导数表达式，以此为基础，分析了二维浅水流动中旋涡的动力学性质；
The vorticity equation was first established and the characteristics of vortex motion in two-dimensional shallow-water flows was analyzed, and then discrete vortex method (DVM) was briefly described.
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