Mobile Prisms for Flow Measurement in Rectangular Channels

Abstract

Flow measurement (both temporary and continuous) in rectangular irrigation channels, sewers or drains, can easily be carried out quickly using measuring flumes. This study presents a particular kind of measuring flume, whose throat section is obtained with a mobile pier-shaped prism in the center of a rectangular channel. This kind of construction allows moving this measuring device from one measuring station to another, if necessary, so that it is absolutely mobile. The experimental study of five similar prisms placed in two different laboratory channels is reported. Particular attention is given to the study of submerged flow conditions because of flow measurements with minimum energy dissipation. Nondimensional analysis is used to find a generalized solution, and the results described are valid for any geometrically similar measuring device. Under submerged flow conditions, the error in discharge measurement—from ±3% to ±6%—is often acceptable in practical applications.