张建梅a,b,钟〓亮a,b,刘珺洁b.密排粗糙床面明渠水流的流速结构[J].水电能源科学,2018,36(10):108-112
密排粗糙床面明渠水流的流速结构
Velocity Structure of Open Channel Flow with Dense Roughness
  
DOI:
中文关键词:  密排粗糙床面  明渠紊流  时均流速分布  脉动流速  空间相关性
英文关键词:bed with dense roughness  open channel turbulence  time averaged velocity distribution  fluctuating velocity  spatial correlation
基金项目:国家自然科学基金资助项目(51509026);重庆市基础科学与前沿技术研究项目(cstc2017jcyjAX0278)
作者单位
张建梅a,b,钟〓亮a,b,刘珺洁b 重庆交通大学 a. 国家内河航道整治工程技术研究中心 b. 水利水运工程教育部重点实验室 重庆 400074 
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中文摘要:
      密排粗糙床面在江河治理工程措施中应用广泛,采用不同直径d的圆形玻璃珠制作了3种密排加糙床面,基于光滑床面和密排加糙床面的8组PIV水槽明渠均匀紊流试验资料,研究床面粗糙对明渠水流流速结构的影响规律。结果表明,密排加糙床面明渠紊流的理论床面位置约在颗粒顶部以下0.15d处;粘性底层以外区域的纵向时均流速垂线分布满足对数公式,卡门常数κ=0.4,积分常数A=9.6~11.8,且A随粗糙雷诺数Re*呈幂函数递增变化;床面加糙对内区流速的影响大于外区。脉动流速u、v的空间自相关系数Cuu、Cvv为正值,空间互相关系数Cuv、Cvu为负值,Cuu云图分布大体呈水平略向上倾斜的椭圆形,Cvv云图分布大致呈圆形,Cuv、Cvu的云图分布总体均呈第2、4象限倾斜的椭圆。流量Q增大后,Cuu分布椭圆形状变得细长,Cvv分布与圆形更为接近,Cuv、Cvu分布椭圆长轴与水平轴的倾角均减小;床面加糙对Cuu影响较小,而对Cvv、Cuv、Cvu的影响较大,加糙后Cvv、Cuv、Cvu绝对值总体减小,空间相关性减弱。
英文摘要:
      Dense bed roughness is widely used in river governance engineering measures. Three kinds of dense roughness beds were made by round glass beads with different diameter d. Based on eight sets of instantaneous velocity data investigated by Particle Image Velocimetry(PIV) measurements in longitudinal sections for open channel flows over smooth and rough beds, the influence of bed roughness on the velocity structure of open channel flow were studied. The results show that the theoretical bed location of open channel turbulence with dense roughness beds is about 0.15d below the top of the beads. Vertical distribution of longitudinal mean velocity in the region outside the viscous sublayer satisfies the logarithmic formula, with the Karman constant κ=0.4 and the integral constant A=9.6 11.8. Furthermore, A increases in a power function with the roughness Reynolds number Re*. The influence of bed roughness on the longitudinal mean velocity in the inner region is greater than that of the outer region. The spatial autocorrelation coefficient of fluctuating velocity Cuu and Cvv is positive, and the spatial intercorrelation coefficient Cuv and Cvu is negative. The cloud chart distribution of Cuu is generally elliptical horizontally slightly upward, and the cloud chart distribution of Cvv is roughly round, while the overall distribution of Cuv and Cvu are second, fourth quadrant ellipses. With the increase of flow Q, the distributed ellipse of Cuu becomes slender, the distribution of Cvv is closer to the circle, and the inclination angles between the long axis and horizontal axis of the distribution ellipse of Cuv and Cvu are both reduced. Bed roughness has little impact on Cuu, but it has a greater impact on Cvv, Cuv, and Cvu. The absolute value of Cvv, Cuv, and Cvu decreases with the increase of bed roughness, which means the spatial correlation is weakened.
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