Flow Resistance Coefficients of Three Sizes of Cast-in-Place Concrete Pipe

摘要

Hydraulic resistance coefficients were determined from head loss measurements made in 48-, 42-, and 36-inchdiameter cast-in-place concrete pipe installations. Data were obtained with the pipes flowing full at discharges less than the design values; from about 10 cubic feet per second to 25 cubic feet per second. Pipe test reaches varied from 1,240 to 3,895 feet. The hydraulic grade line was measured in 10-inch-diameter air vents used as piezometers; discharges were measured using a rectangular weir. Sufficient data were obtained to calculate flow resistance coefficients using the Darcy-Weisbach, Manning, and Scobey equations. The flow resistance coefficients for the 48- and 42-inch pipe and one reach of 36-inch pipe may contain residual losses produced by pipe entrance flow patterns, but the resistance coefficients for one reach of 36-inch pipe are believed to be representative of the values to be expected in long straight reaches. (Author)