Discharge coefficients for different types of side weirs

الملخص EN

Side weirs are extensively used with open channel structures for different purposes such as; raising water level for irrigation and drainage purposes, also to divert a course of excess flow from rivers or channels during the occurrence of flood which is consider the main problem during the wet seasons.

in the present study a series of 18 manufactured laboratory models of different types of side weirs are investigated through a total of 160 test runs.

subcritical flow regime was tested on the side weirs that installed inside the prismatic rectangular main channel.

five different types of side weirs are used namely linear crest of normal rectangle with (θ = 90o), an oblique rectangle which inclined its crest with flow direction by (θ =75o, 60o and 45o), triangular labyrinth with apex angles (δ=90o and120o), semi-hexagonal labyrinth with wall angles (z=30o and 64.7o) and semi-circular labyrinth side weirs.

dimensional analysis for different parameters which influence the behavior of models were carried out, then the equations outlined from multivariable regressions.

for this purpose a statistical software called (SPSS v.22.0) was applied.

finally de Marchi's assumption of constant specific energy along the side weir was checked and approved, moreover the results shows that the coefficient of discharge in labyrinth side weir cross–sections are greater than of the linear crests of rectangular models.