摘要
针对高水头、大流量的泄洪洞有压段出口易出现空化空蚀问题,依托长度比尺为1∶50的物理模型试验对窄缝消能的突扩跌坎式掺气设施水力特性进行研究;并借助Fluent软件探究不同体型参数下的水力特性规律,数值模拟采取VOF多相流模型、RNG k-ε湍流模型、PISO速度压力耦合方程,得出的流量、水面线、流速和时均压强分布与试验实测值最大误差低于10%,可满足工程精度要求。进一步深入研究发现:随着闸门开度减小、出口窄缝宽度增加,侧壁对水流约束降低,纵向拉伸减弱,空腔长度、净空腔长度及净空腔高度均有所增加,且高水位下的各项空腔水力学指标增加趋势大于低水位;其他条件不变时,空腔回水相比射流落点对窄缝收缩比的变化更敏感;随着侧壁由对称收缩逐渐偏转至单侧收缩,最长射流落点位置不变,由侧壁中心逐渐偏转至不收缩侧,且净空腔高度保持不变;采取增大窄缝收缩比及底板坡度的方法可较好解决空腔回水问题。该研究有助于明晰采用窄缝消能的泄洪洞掺气减蚀设施的三维水力学特性,可为相关工程掺气减蚀设计提供借鉴。
Aiming at the cavitation problem at discharge orifice with high head,the hydraulic characteristics of sudden lateral enlargement and bottom drop are investigated based on the length ratio of 1∶50 hydraulic model test.And the numerical simulation uses Fluent software to study the hydraulic characteristic laws under different water body parameters.The calculation uses the VOF multiphase flow model,the RNG k-εturbulence model,and the PISO velocity-pressure coupling equation.The calculated flow rate,water surface line,flow velocity,and time-averaged pressure distribution have a maximum error of less than 10%compared to the measured values from the test,which meets the engineering accuracy requirements.Further study found that as the gate opening decreases and the outlet narrow slit becomes wider,the sidewall constraints on water flow decrease,longitudinal stretching is weakened,and the cavity length,net cavity length,and net cavity height all increase.At high water levels,the growth trend of cavity hydrodynamic metrics exceeds that at low water levels.Assuming all other conditions are equal,cavity backwater exhibits greater sensitivity to slot contraction ratio changes than jet impact points.As the sidewall gradually deflects from symmetric to unilateral contraction,the location of the longest jet fallout point remains constant and the position is gradually deflected from the center to the non-contracting side.Adopting the method of increasing the width of slit and the slope of bottom can better solve the problem of cavity backwater.The results of the study help to understand the three-dimensional hydraulic characteristics of aeration facilities of the discharge orifice adopting slit-type flip bucket,which can provide a reference for the sizing of similar projects.
作者
赵歆萌
刘亚坤
张帝
卢洋亮
ZHAO Xin-meng;LIU Ya-kun;ZHANG Di;LU Yang-liang(School of Infrastructure Engineering,Dalian University of Technology,Dalian 116024,Liaoning Province,China)
出处
《中国农村水利水电》
北大核心
2026年第3期134-139,147,共7页
China Rural Water and Hydropower
基金
国家自然科学基金项目(52179060)。
关键词
高速水流
掺气减蚀
突扩跌坎
空腔回水
窄缝消能
high-speed water flow
aeration cavitation-alleviation
sudden lateral enlargement and bottom drop
cavity backwater
slittype flip buckets
