Author(s): S. M. Borghei; A. Behrangi; A. R. Daemi
Linked Author(s):
Keywords: Open-channel; Junction; Experimental test; Shape index; Froude number
Abstract: Flow at open-channel junction is concern of many disciplines in hydraulic engineering, e.g.; river studies, surface drainage problems and, water and wastewater projects. Since many variables are involved, no wonder ample study is required for better understanding of the flow problem while limited results are available. Hence, in this paper the influence of two variables, which have been less studied experimentally, are presented. First the effect of branch channel to main channel width and, second, the geometry of the channels connection. Three width ratios (branch to upstream channel width) of 1,0. 75 and 0.5 have been tested. Also, two connection geometry of sharp and 45o at the entrance from branch to main channel have been selected. For all the tests the central line of branch to main channel is a 90 degrees connection and the flow is subcritical. Other variables are the discharge ratio (5 different ratios from 0.05 to 0.95) and, four different downstream Froude numbers (from 0.22 to 0.53). The results are presented in graph forms showing the effect of the variables on the separation dimensions downstream of the junction (shape index) and, the depth ratio in the two channels and the main channel. The results show that a small angle at the connection point can reduce the separation length and width dramatically. This means smaller turbulence domination at the junction which can reduce erosion and sedimentation potential of the junction.
Year: 2003