Hydraulics of Perforated Terrace Inlet Risers

ABSTRACT TERRACE inlet risers perforated with circular and slot orifices were tested in the laboratory. The orifice discharge coefficient for a circular orifice in the cylindrical surface of a riser was found to be significantly larger than for a circular orifice in a flat plate. A simple theoretical equation was found to provide good estimates for riser discharge when correct values of discharge coefficient are used. Side orifices should be evenly distributed around the circumference of the riser to reduce vibration.