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JOURNAL OF HYDROELECTRIC ENGINEERING ›› 2016, Vol. 35 ›› Issue (12): 77-85.doi: 10.11660/slfdxb.20161208

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Development of turbulent boundary layer in submerged hydraulic jump regions of rectangular flat bottom channels

  

  • Online:2016-12-25 Published:2016-12-25

Abstract: Methods for determining the development of a turbulent boundary layer and its wall distances of half maximum velocity and zero-velocity line in submerged hydraulic jump regions are presented in this paper. To derive these methods, we have applied Verhoff’s formula of local velocity distribution in wall jet regions and the momentum integral equation of turbulent boundary layers to a detailed analysis of Rajaratnam’s experimental data: local velocity distribution, local maximum velocity, bed shear stress and the wall distance of half maximum velocity collected from the submerged hydraulic jump regions in a rectangular flat-bottom channel. The analysis gives an approximate formula of maximum velocity distribution and theoretical formulae for calculating the thickness of a turbulent boundary layer and its wall distances of half maximum velocity and zero-velocity line. Using the measured data, we verified the new formulae and improved the coefficient in Rajaratnam’s empirical equation for calculation of the wall distance of half maximum velocity. The results show that the development of a turbulent boundary layer in submerged hydraulic jump regions is rather similar to that in the smooth plate case: its thickness is proportional to the 1.14 powers of wall distance x and inversely proportional to the one fifth power of . And the wall distances of half maximum velocity and zero-velocity line are proportional to x and inversely proportional to the Reynolds number at the initial section of the jump.

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