基于流态辨识的弧形闸门过流计算

New discharge algorithms of radial gates based on the flow regime identification

过闸流量的精确计算是实现调水工程闸门自动控制、调度运行系统仿真和工程适时、适量供水的重要前提。在闸后收缩断面为低弗劳德数(约Fr<1.7)的淹没孔流条件下,现有弧形闸门过流计算的经验系数模型和量纲分析模型流量预测误差较大。基于已有试验数据分析,研究提出了闸孔淹没出流的高Fr区和低Fr区的流态辨识参数——综合能耗系数Er,定义为相对开度e/H和潜流比Xr之和,即Er=e/H+Xr,相应的流态辨识方法为:Er<1为高Fr的部分淹没孔流,Er≥1为低Fr的完全淹没孔流。针对闸孔出流的不同流态,即自由孔流、部分淹没孔流和完全淹没孔流,分别建立相应的流量计算模型,采用最小二乘辨识进行模型参数的估计,实例验证表明流态辨识模型整体的预测精度较高,80%预测流量的相对误差|EQ|<±10%,且EQ近似呈正态分布。本文提出的流态辨识方法和计算模型为过闸流量的精确计算提供了新的思路和方法。

Accurate estimation of flow discharge though radial gates in water diversion projects is an essential precondition for automatic control of gates, simulation of the operation and dispatching system, etc..The flow discharges predicted by the conventional empirical coefficient model and dimensionless analysis model are of large errors under the submerged flow conditions with low jet Froude number at vena contracta. In this paper,the influence factors of discharge coefficient are analyzed. A new parameter Er is proposed to identify flow regime for submerged flow,which is defined as Er=e/H＋Xr. When Er〈1,the submerged flow is of large jet Froude number,and when Er≥1,the submerged flow is of low jet Froude number. Based on the above flow regime identification,the discharge algorithms are established for free flow,partially submerged flow and totally submerged flow,respectively. Then,the model parameters are estimated by the least squares method. The verifying results show that the discharges predicted by new discharge algorithms are of higher precision. The relative errors ｜EQ｜ of 80% tests are less than 10%,and EQ is close to the normal distribution. The flow regime identification criterions and the discharge algorithms proposed in this paper can provide new ideas for the accurate prediction of discharge through gates.