Electronic Thesis and Dissertation Repository


Master of Engineering Science


Civil and Environmental Engineering


Raouf E. Baddour


An unsteady experimental study was completed with the intention of identifying a transition region between partially full weir flow and fully developed orifice flow for a circular sharp-edged orifice. Three orifices of different diameter were tested. The head-discharge relationships were obtained by pressure recordings and directly compared by using dimensional analysis. The presence of true weir and orifice flow behaviour was evaluated by an original technique where the head exponent in the head-discharge relationship is considered. The study found that true orifice behaviour was achieved in the experiments. Correspondingly, based on the head exponent, no evidence was obtained to support the existence of a different flow behaviour within the transition. Nevertheless, the experimental data have indicated that corrections are required to be applied to the discharge coefficient in the transition domain. A set of steady state experiments verified the unsteady data results in the orifice flow regime. Discharge coefficients were calculated and predicted by a fitted equation for a circular sharp-edged orifice across the entire range of head. Comparisons to the commonly used orifice equation validate its use for design.