Abstract: Based on a 1:100-scale model of the Jinghong hydropower station, we study the hydrodynamics and regulatory responses of a stilling pool under the jets from a tail-flaring pier spillway, focusing on the influence of water cushion depth, unit discharge and opening mode on hydrodynamic pressure. We found that time-average pressure is dominated by water cushion depth, independent of the unit discharge and increasing with this depth, while pressure fluctuations depend on these two factors, reduced by a thinner cushion and intensified by a larger unit discharge. And dynamic water pressure is different in different gate operation modes. In the test, as the opening mode of surface outlets shifts from the alternate pattern to sectional pattern, the peak values of fluctuating pressure at their centerlines and at the pier centerlines are weakened.

Key words: flaring gate pier, underflow energy dissipation, operation mode, regulation response, hydrodynamic pressure, model test