Hydraulic performance of a portable triangular-central flume for rectangular channels

【Objective】Accurate measurement of channel flow is essential for effective irrigation district management. This study evaluates the hydraulic performance of a portable triangular-central flume for measuring water flow in rectangular channels. 【Method】Physical tests were conducted under six different flow rates (0.031-0.093 m3/s), four top angles (45°-90°), and three shrinkage ratios (0.375-0.625). Hydraulic performance parameters, including water surface profile, Froude number, backwater height, and head loss under varying operating conditions, were obtained through theoretical calculations and analysis. Flow equations were derived using both hydraulic and dimensional analyses.【Result】The water surface profile variation can be divided into four distinct regions: the upstream backwater zone, the rapid transition zone, the post-jump transition zone, and the downstream stable zone. The upstream Froude number ranged from 0.21 to 0.39, while backwater height varied between 4.28 cm and 18.53 cm. Head loss ranged from 7.13% to 32.82%. The relative error of the flow equations derived from hydraulic and dimensional analyses was between -5.98% and 5.02% and between -3.23% and 2.03%, respectively. The optimal location for measuring water depth in the flume was determined to be 0.5 m upstream of the flume throat. 【Conclusion】The flow equation derived from dimensional analysis provides more accurate measurements compared to conventional flumes. The flume exhibits optimal hydraulic performance when the shrinkage ratio is between 0.5 and 0.625. Among the tested top angles, a 60° configuration yielded the best hydraulic performance. The portable triangular-central flume offers a simple yet effective method for measuring flow while maintaining strong hydraulic efficiency. These findings serve as a valuable reference for designing flow measurement flumes in irrigation canal systems.