摘要
【目的】研究低佛氏数(Fr1)水跃紊流的水力特性。【方法】采用VOF方法处理闸门上、下游表面,用二维RNG型k-ε紊流数学模型,对低佛氏数(Fr1=2.0~4.5)水跃紊流进行数值模拟,研究了不同低佛氏数水跃的跃后水深、水跃长度及流速分布,分析了水跃区及其下游明渠流区压强、紊动能、耗散率和水跃消能率的特性。【结果】淹没系数大于1.2时,水跃长度均大于其他经验公式计算的水跃长度,且水跃长度增幅随佛氏数的增加而增大。水跃区断面各点时均流速最大值沿程减小;跃后明渠流区,断面各点平均流速沿程无明显变化。水跃区主流与漩滚交界处附近,特别是泄水闸门附近的紊动能及耗散率均最大。随着佛氏数的增加,理论和实际消能率均增大,且理论消能率大于考虑了跃后紊动能的实际消能率。【结论】低水头水利枢纽泄洪功率较大,应充分考虑低佛氏数水跃实际消能率低的水力特性,设计合理的消能设施以解决其消能防冲问题。
【Objective】The research studied the hydraulic jump characteristic of low Froude number.【Method】By using VOF method in water surface upstream and downstram of the gate and 2-d k-ε RNG turbulence model,hydraulic jump with low Froude number(Fr1=2.0-4.5) was simulated numerically.Water depth after hydraulic jump,length of hydraulic jump and distribution of flow velocity of hydraulic jump with low Froude number were analyzed.Furthermore,pressure,turbulent kinetic energy,turbulent dissipation and coefficient of energy dissipation in the hydraulic jump region and the open cannel flow region were studied.【Result】The length of hydraulic jump whose degree of submergence is more than 1.2 is longer than that of calculated by empirical formula,and increases along with the increase of Froude number.The maximum velocity reduces along the flowing of the main flow in the hydraulic jump region,and the reduction of the average velocity in section is small in open channel flow region after hydraulic jump.The pressure distribution of hydraulic jump is closely related to flow aeration.Turbulent kinetic energy and coefficient of energy dissipation are the maximum near the boundary of the main flow and ground droller in the hydraulic jump.The higher the Froude number is,the higher the theoretical and practical coefficient of energy dissipation is.The theory coefficient of energy dissipation is higher than actual coefficient considering the turbulent kinetic energy after hydraulic jump.【Conclusion】Because low-head key water control project has larger flood discharge power,less energy dissipation hydraulic characteristic of hydraulic jump with low Froude number should be seriously considered,and reasonable energy dissipation instrument should be designed to solve its problems of energy dissipation and erosion-control.
出处
《西北农林科技大学学报(自然科学版)》
CSCD
北大核心
2012年第1期227-234,共8页
Journal of Northwest A&F University(Natural Science Edition)
基金
水沙科学及水灾害防治重点实验室开放基金项目(20102010SS08)
长沙理工大学科技创新团队建设计划资助项目(2007CX04)
关键词
低佛氏数水跃
紊流数值模拟
水跃区
明渠流区
hydraulic jump with low Froude number
numerical simulation of turbulence flow
hydraulic jump region
open channel flow region