琴键堰过流水力特性数值模拟

Numerical simulation of hydraulic characteristics of piano-key weir

琴键堰是一种新型的迷宫堰结构形式,其特点是相同堰宽、水头条件下泄流能力提升显著,采用RNG k-ε型湍流数学模型,VOF法处理自由水面,建立三维数学模型。通过对不同工况琴键堰体型的模拟计算,获得三维流场水流流态、流速等信息。结果表明:(1)采用Fluent软件对琴键堰进行数值模拟的适用性强,并验证了琴键堰的泄流效果显著;(2)琴键堰的三维流场流态复杂,具有三元水流的性质,堰上水头的变化影响琴键堰的泄流能力;(3)上、下游处水流呈明渠流状态,速度最小,为0.2m/s,流经堰体时形成水舌,流速增大,水舌与堰壁间空腔处有通气孔掺气,形成漩涡区,气体流速2m/s,水舌入水后有水气混掺。利用数值模拟技术,使获得的流场信息更加详尽,为进一步研究琴键堰流场特性奠定基础。

The piano-key weir is a new form of labyrinth weir and is characterized by a significant increase in the discharge capacity under the same weir width and water head condition.We used the RNGk-εtype turbulence mathematical model and the VOF method to deal with the free water surface and to establish a three-dimensional mathematical model.Through the calculation of the shape of the pianokey weir in different conditions,we obtained the flow regime,flow velocity,and other information of the three-dimensional flow field.The results were as follows.(1)The software Fluent was applicable to the numerical simulation of the piano-key weir,and it proved the remarkable discharge effect of the piano-key weir.(2)The three-dimensional flow field of the piano-key weir had a complex flow regime and the properties of ternary flow.The change of weir head would affect the discharge capacity of the piano-key weir.(3)The flow at the upper and lower reaches showed the state of open channel flow with a minimum velocity of 0.2 m/s.When the flow passed the weir,it formed water jets with increased velocity.There was air entering from the ventilation holes at the cavities between the water jets and the weir wall,forming a whirlpool.The air flow velocity was 2 m/s.After the water jets entered the water,there was air mixed with the water.The numerical simulation technique generated more detailed flow field information,which laid the foundation for further study of the flow field characteristics of the piano-key weir.