水工消能设施消能率的理论分析及计算方法

由于水工消能设施内水流流态复杂,当水流流态为恒定急变流和非恒定流时,现有消能率计算公式不能适用。为此,基于水工消能设施内流体能量消散的本质,通过能量方程推导出适用于恒定流和非恒定流计算消能率的一般公式,利用重积分数值计算方法和离散函数求导法则处理所提的消能率计算公式,并给出恒定均匀流、恒定急变流、非恒定流条件下消能率的具体计算方法。最后,以平原区某水闸为例,采用所提公式计算该闸闸门开启后10~40s内消力池的消能率。理论分析及计算案例表明,所提消能率计算公式可适用于复杂流态下消能率计算,通过重积分数值计算方法和离散函数求导法则处理后的计算公式具有实用性和可行性,可较好地解决恒定急变流和非恒定流条件下消能率无法计算或计算结果偏差较大的问题。

Theoretical Analysis and Calculation Method of Energy Dissipation Ratio of Hydraulic Energy Dissipation Facilities

Due to the complexity of flow pattern in hydraulic energy dissipation facilities,when the flow pattern is rapidly varied to steady flow and unsteady flow,the existing calculation formula of energy dissipation ratio cannot be applied.In order to solve this problem,based on the essence of fluid energy dissipation in hydraulic energy dissipation facilities,this paper deduces the general formula suitable for calculating the energy dissipation ratio of steady flow and unsteady flow through the energy equation,processes the formula for calculating the energy dissipation ratio by using the numerical calculation method of multiple integral and the derivation rule of discrete function,and gives the specific calculation method of energy dissipation ratio at the conditions of uniform flow,rapidly varied steady flow and unsteady flow.Finally,taking a sluice in the plain as an example,the proposed formula is used to calculate the energy dissipation ratio of the energy dissipation tank within 10to 40seconds after the sluice gate is opened.Theoretical analysis and calculation examples show that the proposed formula can be applied to the calculation of the energy dissipation ratio in complex flow pattern.The formula processed by the numerical calculation method of multiple integral and the derivation rule of discrete function is practical and feasible,which can better solve the problem that the energy dissipation ratio cannot be calculated or the calculation result has large deviation in the condition of rapidly varied steady flow and unsteady flow.