水电站排沙漏斗水沙运动规律

以燕子崖水电站为例,采用流体体积模型(VOF)方法耦合、雷诺应力模型(RSM)、离散控制方程、五阶Runge-Kutta变步长积分法模拟排沙漏斗水沙运动规律,并通过物理模型试验论证数学模型计算合理性.结果表明:排沙漏斗切向流速总体呈现中间小、两头大的特点,在排沙底孔位置产生空气漏斗,空气漏斗周围产生强迫涡流;径向流速随径向位置半径增大而先小后大,方向由内到外,在漏斗排沙底孔位置存在向内的、较大的径向流速;轴向速度值随径向位置半径增大作上下波动而波幅逐渐减小,轴向流速波动变化较为强烈并形成一个势涡;含沙量垂向分布为上小、下大分布,含泥沙量在近底部附近较高,底部附近形成较高含泥沙水流;在漏斗圆形边壁的约束下水体产生一个强迫涡流,强迫涡流具有高排沙能力,将漏斗排沙底孔附近的泥沙快速带入排沙底孔,通过与排沙底孔连接的排沙廊道排走泥沙.切向、轴向、径向流速以及含泥量的模型试验值与数学模型计算值相差较小.

Water and sediment motion law of sediment drainage funnel in hydropower station

Taking Yanziya hydropower station as an example,the water and sediment motion law of sediment drainage funnel was simulated by using volume of fluid(VOF)model,Reynolds stress model(RSM),discrete N-S equations and fifth-order Runge-Kutta variable step integration method,and the rationality of mathematical model predictions was demonstrated through physical model test.The results show that the tangential velocity of the sediment drainage funnel is generally small in the middle and large at both ends.The air funnel is generated in the bottom of the sediment drainage funnel,and a forced eddy current is generated around the air funnel.The radial velocity magnitude is small at first and then gets large with increasing radius,and the velocity direction is from the inside to the outside.There is an inward and larger radial velocity in the bottom of the sediment drainage funnel.The axial velocity magnitude is in oscillation,but its amplitude reduces with increasing radius.A top-low and bottom-high vertical distribution of sediment concentration is exhibited,a higher sediment content is found near the bottom,resulting in a higher sediment flow near the bottom.Under constraint of the funnel circular side wall,the water body generates a forced eddy with a strong sediment discharge capacity.The eddy can bring the sediment near the sand discharging bottom hole into the hole quickly,then the sediment is discharged downstream via a sand discharge tunnel connected with the hole.The differences of the predicted tangential,axial,radial velocities,and sediment content from the counterparts in model test are small.