ANALYSIS OF EXISTING METHODS FOR CALCULATING THE ROUGHNESS COEFFICIENT OF CHANNELS ALONG THE PERIMETER OF THE CHANNEL
Joldassov S. Tattibaev S. Bimurzayeva Z. Bayzhigitova M. Loginov G.
2023National Academy of Sciences of the Republic of Kazakhstan
News of the National Academy of Sciences of the Republic of Kazakhstan, Series of Geology and Technical Sciences
2023#1Issue 45756 - 71 pp.
The scientific work examines the issues of the channel roughness coefficient and the uniform movement of water in channels with bottom roughness. The analysis of existing methods for calculating the roughness coefficient of channels along the perimeter of the channel is given. The methods of determining the roughness coefficient of famous scientists such as P.N. Belokon, G.K. Lotter, N.N. Pavlovsky for channels consisting of two or three slopes along the perimeter of the channel are presented and analyzed. When designing channels with a soil base, the reduced roughness coefficient of the channel, which forms the basis of the resistance of the plantar structure along the length of the channel, plays a decisive role. Currently, there are a number of computational relationships proposed for hydraulic calculations of water flow along the perimeter of the channel. A number of researchers claim that the soil of the channel bottom simulates the flow movement in different channels with the flow movement under the ice layer. But, it should be borne in mind that the soil of the channel bottom has its own characteristic (specific) features of water movement in open channels with different roughness and under ice cover. The calculation formulas proposed by a number of authors for channels with different lengths along the perimeter cannot be used directly for hydraulic calculations of the flow under the ice cover, and vice versa, the equations of water flow under the ice cover do not apply even for channels with different roughness along the perimeter. In general, the solution to the main computational relationship is to determine the perimeters and areas included in separate disparate sections. Determining the perimeters of individual parts does not create any special difficulties and is defined as the corresponding face of a geometric figure. Taking into account the fact that the edge of the wall should lie on the considered sole of the channel. But to determine the area of the figures adjacent to the walls in an individual appearance is quite a complicated matter. Approaches of well-known scientists in the scientific literature, such as P.N. Belokon, G.K. Lotter, N.N.Pavlovsky and E.E. Schiperko are based on the phenomenon of flow and large assumptions about the equality of the hydraulic radii of individual parts and the whole channel, as well as the equality of the average speeds of individual parts and the whole flow, but in fact they are not. Current measurements in the laboratory, performed by us and other authors, show that they differ in magnitude and allow significant errors in calculations. Thus, we came to the conclusion that an attempt to solve the problem of the reduced roughness coefficient using generally accepted approaches did not allow us to obtain the desired results: it is not enough to use only the equation of uniform motion, and, therefore, it is necessary to consider other ways to solve the problem. In our opinion, the simplest method is used by all authors who have dealt with the calculation of channels of varying degrees of complexity.
average velocity , channel , channel cross-section , channel perimeter , hydraulic radius , roughness coefficient , steady motion , uniform motion
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M.Kh. Dulaty Taraz Regional university, Taraz, Kazakhstan
Kyrgyz-Russian-Slavic University, Kyrgyzstan
M.Kh. Dulaty Taraz Regional university
Kyrgyz-Russian-Slavic University
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