基于甘肃某抽水蓄能电站泄洪洞洞内消能设计,探讨在流量及底坡恒定的条件下,台阶尺寸与消能率的相关关系,探寻台阶尺寸的初拟原则,采用现行NB/T 10867-2021《溢洪道设计规范》中跌落流上限及滑行流下限的经验公式(坡角 范围为2.86°～59.53°)进行台阶消能流态的初步判别,通过Chanson半经验公式理论计算和CFD数值模拟水工隧洞底板布置不同台阶尺寸对应的消能特性.结果表明:在流量及坡度不变的情况下,台阶尺寸(台阶步长及高度)对消能率的影响有限;台阶尺寸越大,水力要素受流动边界条件影响和扰动越明显;初拟台阶尺寸时,应分析水流掺气点位置及出现掺气均匀流位置随台阶尺寸变化向上游移动的速率,同时结合实际边界条件、便于施工及后期运维等方面综合考虑,台阶高差宜控制在0.20～0.60 m.
Study on the Energy Dissipation Type of the Non-pressure Spillway Tunnel Steps in Pumped-storage Power Station
Based on the energy dissipation design of a spillway tunnel in a pumped-storage power station in Gansu Province,the relationship be-tween the step size and the energy dissipation rate under the conditions of constant flow and bottom slope is discussed,and the preliminary princi-ple of the step size is explored.The paper uses the empirical formula for the upper limit of falling flow and lower limit of sliding flow(slope angle range is2.86°～59.53°)in the current NB/T10867-2021 Code for Design of Spillways to preliminarily identify the flow regime of step energy dis-sipation.The energy dissipation characteristics corresponding to different step sizes of the hydraulic tunnel bottom plate are calculated by Chanson semi-empirical formula theory and CFD numerical simulation.The results show that under the conditions of constant flow and slope,the influence of step size(step length and height)on energy dissipation rate is limited;the larger the step size,the more obvious the influence and disturbance of hydraulic factors by flow boundary conditions;when initially determining the step size,it is necessary to analyze the location of the air entrain-ment point of the water flow and the rate of upstream movement of the quasi-uniform flow position as the step size changes,while taking into ac-count practical flow boundary conditions,ease of construction,and later operation and maintenance to ensure reasonable,economical,safe,and reliable engineering design.The height difference of the steps should be controlled within the range of 0.20 m to 0.60 m.
pumped-storage power stationspillway tunnelstepped dissipationflow regimeenergy dissipation rate
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