ВИЗНАЧЕННЯ КОЕФІЦІЄНТУ ШОРСТКОСТІ ДЛЯ РОЗРАХУНКУ ПОТОКУ НЕУСТАЛЕНОГО РУХУ РІДИНИ

Abstract

The analysis of the literature devoted to calculation of hydrotechnical structures showed that there are recommendations that take into account the influence roughness of the channel on magnitude transformation transit flow of liquid along the length of the channel. But these recommendations are difficult to apply to reclamation systems, which include complexes of hydraulic engineering and transport facilities, because they do not take into account the characteristic features of unsteady fluid movement in such systems. Unfortunately, as of today, this issue has not been adequately addressed in modern scientific literature. The article considers the issue of determining the roughness coefficient based on the materials of field experiments on irrigation systems of Ukraine for its further use in the Saint-Venant equations for unsteady water movement in open prismatic channels. At one time, professor V.O. Bolshakov applied the method of running according to the implicit difference scheme, provided that the roughness coefficients are known, to solve the Saint-Venant equations. The authors conducted an analysis errors of field measurements of maximum depths, calculation area of live sections, etc. The absolute error of finding the drop in water levels in individual sections of the channel was determined. The results. Among the issues that were covered in the discussed publication, the main attention was paid to the issue of studying the influence of the roughness coefficient on flow elements during unsteady motion in meliorational (irrigation) systems. Also, the characteristics conducted field measurements are given, a detailed overview field data is provided, and the measured parameters at different sections research channel are listed. Conclusions. An indicative evaluation and analysis errors of the performed measurements was carried out, and recommendations were given for determining the average values of roughness coefficients for irrigation channels (channels) with a well-planned bottom and slopes, as well as for banks not covered with vegetation. The results of data processing of field observations are summarized in a table, which presents a comparison calculated values of the roughness coefficients.