直角折线堰不同堰体长度变化下的过流能力及拟合分析

Overflow capacity and fitting analysis of right-angle polylineweir with different weir length variations

为探究自由出流条件下,直角折线堰各部分堰体长度变化时的过流能力,通过FLOW-3D软件建立直角折线堰数学模型,采用RNG k-ε湍流模型与TruVOF自由液面追踪方法,对侧堰长度、位置改变的9组直角折线堰进行数值模拟计算,进而分析相同堰顶水头条件下的前堰、侧堰、后堰过流能力变化规律.结果表明:随着侧堰长度的增加,侧堰过流能力逐渐增大,但增幅减小;前堰、后堰过流能力均有所下降,但后堰降幅更大;侧堰过流能力随着侧堰位置的改变(前堰长度增加、后堰长度减小)呈现先增加后减小的变化趋势;而前堰、后堰过流能力则与其自身长度呈非线性正相关关系.在此基础上,拟合出堰顶相对水头变化下的溢流前缘不同堰体长度流量计算公式,并给出直角折线堰侧堰位于0.45倍河道宽度时过流能力最大、侧堰长度达1.30倍河道宽度时过流能力增幅趋于平缓的结论.

In order to explore the overflow capacity of each part of the right-angle broken line weir(front weir,side weir and back weir)when the length of the weir body changes under free outflow conditions,a mathematical model of a right-angle polyline weir was established by FLOW-3D software.The RNG k-εturbulence model and the TruVOF free surface tracking method were used to calculate the data of nine groups of right-angle polyline weirs with different lengths and positions of the side weirs.Furthermore,the changes law of the overflow capacity of the front,side and back weirs under the same head conditions was analyzed.The results show that with the increase of the length of the side weir,the overflow capacity of the side weir increases,however the increase relatively slows down.Meanwhile,the overflow capacity of the front weir and the back weir decreases,but the decrease range in capacity of the back weir is bigger than that of the front weir.With the change of the side weir position(the length of the front weir increases and the length of the back weir decreases),the overflow capacity of the side weir increases,showing a trend of first increasing and then decreasing,while the overflow capacity of the front weir and the back weir has a non-linear positive correlation with their own length.On this basis,the flow calculation equation for different weir lengths at the leading edge of the overflow under the change of relative head at the top of the weir is fitted.It is concluded that the maximum overflow capacity is reached when the side weir of the right-angle polyline weir is located at 0.45 times the channel width,and the increase of overflow capacity tends to level off when the side weir length of the right-angle polyline weir reaches 1.30 times the channel width.