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Corresponding Author

Saqr, A.

Subject Area

Civil and Environmental Engineering

Article Type

Original Study

Abstract

The main objective of this research work is to investigate the energy coefficient (α) and momentum coefficient (β) for some Egyptian irrigation canals. Six cases of study from them having different degrees, starting from rayyahs to distributer canals with 10 successive cross sections for each reach, were carefully selected with discharge values ranged from 489.7 m3/s to 0.4 m3/s. The different properties and flow characteristics of each cross section were obtained. The arithmetic method was used in the computation process of α and β values due to its accuracy using a prepared excel program to facilitate the calculations. It was found that the computed values of α and β approximately match with Chow’s table with average values of about 1.30 and 1.11 respectively, for canals under study, which could be used for field applications. It was also found that the average values of α and β for each canal increased with the increase of the canal degree but the maximum and the minimum values may be independent of the canal degree. General relationships relating α and β for each canal and for all canals under study have been derived. Moreover, correlation relationships for both α and β with a ratio correlating maximum and mean velocities ( ), Manning’s roughness coefficient (n), and different values of discharge and channel characteristics were performed. The cross section properties had intangible effect on the values of both α and β but these values were strongly dependent on the velocity distribution shape. Froude number had a pronounced effect on the value of α and β but Reynolds number could have a negligible effect.

Keywords

Energy coefficient; Momentum coefficient; Egyptian irrigation canals; Manning’s coefficient; Froude Number; Reynolds number

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