Author(s): S. A. Ead; S. Shabayek; N. Rajaratnam
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Keywords: No Keywords
Abstract: This paper presents simple analysis of uniform open channel flow in circular culverts laid on a slope S and introduces a dimensionless discharge parameter Q*. When the pipe just flows full, Q* becomes Q*f equal to 0.312/n* which varies inversely with a modified Manning's n written as n* equal to ▲ where g is the acceleration due to gravity and D is the internal pipe diameter. This relationship has been checked with experimental observations of Straub and Morris (1950a) and the authors for smooth and corrugated pipes. This criterion also indicates that the discharge parameter ▲ commonly used in culvert flow calculations assumes a certain value when the pipe just runs full, for a given value of n and D, which varies directly with ▲. Experiments for this study were conducted using a circular corrugated pipe of 10 m length and 0.622 m and 0.311 m diameters laid on three slopes S of 0.6, 1.1, and 2.6% and a range of discharges from 27 to 235 L/s. Also, observations of Rajaratnam and Ead (2003) on a smooth glass circular pipe of internal diameter D of44 mm with a length of 2·45 m laid on a slope of 6.7% was used in the analysis. The Manning's n for the corrugated and glass pipes was found to be equal to 0.023 and0.0123, respectively.
Year: 2009