Classification and review on flowmeter design schemes with constrictors for open watercourses

Abstract

In the context of a returning shortage of water resources, the problem of their conservation and rational use of water is of paramount importance. This necessitates the improvement of the water accounting system in hydro-reclamation. In water metering, the problem of water discharge in canals with a uniform flow regime is the most difficult: traditional methods of measurement: “velocity – area” and variable level difference with constriction devices, in general, meet modern requirement sand in the near future will remain the most common. The study was aimed at systematizing and classifying the design features of flow meters with constricting devices, as well as substantiating the principles of their placement on open irrigation and drainage systems. For this purpose, the following tasks were set and successfully solved: substantiation of the principles of placement of measuring instruments on open HMS, selection of optimal flow meter designs and determination of factors affecting the measurement error when using flow meters with constricting devices. Analyses have been carried out that indicate that the error of the flow coefficient increases with a decrease in the inclination of the side faces of spillways with a thin wall. The distribution of error is asymmetrical due to nonlinear changes in the flow coefficients during changes in the shape of the compressed cross-section. As a result of the study, it was revealed that the method of variable level difference with constriction devices has a number of advantages, including ease of manufacture and installation, as well as the possibility of using indirect calibration methods.