摘要
对于深山峡谷区的水利枢纽工程,斜向进水矩形消力井的消能方案能够很好地适应狭窄地形条件,其消能效果与斜向入射水流的紊动及能量耗散直接相关。采用大涡模拟方法研究特定流量下矩形消力井射流的紊动特性,结果表明:射流方向淹没主流轴线区域主要表现为无旋运动,尺度不一、强度各异的旋转涡旋在水股周围富集(射流沿程相对涡量绝对值降幅为74%~92%)。射流前段涡旋强度较大,涡结构破碎,分布厚度较小;射流中段涡旋的分离及融合范围逐渐扩大,相邻涡旋区逐步嵌套成条状结构,涡旋强度明显降低;射流后段(偏折以后的潜射水流段)紊流涡进一步破碎、扭曲,并向周围扩散,涡旋强度进一步减小。射流紊动强度呈现明显的中心低、周围高的分布特点,射流周围紊动强度沿程分布具有一定的自相似性,射流前段和中段的水股周围紊动强度沿程逐渐增大(增幅为12%~14%),射流后段紊动强度在四周趋于均匀,但沿程逐渐减小(降幅约为28%)。射流紊动耗散主要分布在水股边缘剪切层区(动能衰减率达到83%~91%),射流前段紊动耗散不明显,携带动能仍较大,射流中段紊动耗散率沿程增大,射流后段紊动耗散逐渐趋弱。综上可知,射流涡旋及其与周围水体之间的能量交换是射流紊动耗散的主要原因,能量耗散主要发生于射流偏折前的中段区域,该段射流动能衰减超过60%。
Rectangular dissipation wells with oblique inlets are well suited to narrow terrains of remote mountainous areas;however,the dissipation effect of the wells is directly affected by the turbulence and energy dissipation of the oblique jet.Here,the large eddy simulation method is used to study the turbulence characteristics of the jet in a rectangular dissipation well under a specific flow rate.The results show that the axis area of the primary submerged flow at the jet direction displays an irrotational motion,whereas rotating vortices of varying sizes and strengths are concentrated around the water stream(absolute reduction rate of relative vortices along the jet falls in the range of 74%-92%).The vortex intensity is greater in the front part of the jet,where the vortex structure is visibly disrupted and the distribution thickness is small.In the middle section of the jet,the range of vortex separation and fusion gradually expands,the adjacent vortex areas begin to form strip structures,and the vortex intensity decreases significantly.In the rear section of the jet,the turbulent vortex is further disrupted,twisted,and spreads outwards,resulting in a further decrease in vortex intensity.The distribution of turbulence intensity around the jet exhibits a clear pattern,with low intensity in the center and high intensity around the jet.This distribution also demonstrates a certain self-similarity.Specifically,the turbulence intensity gradually increases along the path of the jet water stream in the front and middle sections(an increase of 12%-14%).In the rear section,the turbulence intensity tends to be more uniform around the jet,but gradually decreases as it progresses(a decrease of about 28%).The turbulence dissipation of the jet is primarily concentrated in the shear layer region at the periphery of the jet(kinetic energy attenuation rate ranges from 83%to 91%).In the front section of the jet,the turbulence dissipation is not prominent,and it still carries a significant amount of kinetic energy.As the jet progresses,the turbulence dissipation rate increases in the middle section,but gradually decreases in the rear section.It is evident that the primary cause of the dissipation of jet turbulence is the energy exchange between the jet vortex and the surrounding water body.The energy dissipation primarily takes place in the mid-region prior to the jet deflection,and the kinetic energy attenuation of the jet is greater than 60%.
作者
和云秋
邱勇
邱正魁
刘杭铭
王玉骁
HE Yunqiu;QIU Yong;QIU Zhengkui;LIU Hangming;WANG Yuxiao(College of Water Conservancy,Yunnan Agricultural University,Kunming 650201,China;Yunnan Nanyang Water Conservancy and Hydropower Survey and Design Co.,Ltd.,Qujing 655000,China)
出处
《水资源与水工程学报》
CSCD
北大核心
2024年第5期123-129,共7页
Journal of Water Resources and Water Engineering
基金
兴滇英才支持计划项目(202201788)。
关键词
矩形消力井
斜向射流
紊动耗散
紊动强度
涡旋
大涡模拟
rectangular dissipation well
oblique jet
turbulence dissipation
turbulence intensity
vortex
large eddy simulation
