The effects of morphometric elements of the channel on hydraulic resistance of machine channels of pumping stations

Abstract

Presents the results of hydraulic studies in pressureless and pressure water conduits, the results of which showed that the dependences obtained for calculating the hydraulic resistance in round pressure pipes cannot be distributed without the corresponding adjustments of pressureless channels (provided that the diameter of the pipe is replaced in the corresponding calculations with a value where hydraulic radius). In particular, it follows (and this is confirmed by the data of the corresponding experimental studies published in the literature) that in the case of pressureless channels, the pressure loss coefficient, and therefore the pressure loss, depends not only on the relative roughness and Reynolds number, but also on the shape of the cross section the channel. Moreover, if for hydraulically smooth pressureless channels this dependence can be considered to a first approximation clarified, then for channels whose wetted surface is characterized by the presence of a certain roughness, the question of its influence, as well as the shape of the channel cross section on the pressure loss, is far from roughly approximate solution. The paper also considers the general equation of fluid motion in pressureless channels and the functional dependences of the coefficient of hydraulic friction on the Reynolds number, relative roughness, and on the shape of the living section of the channel; resistance formulas are first for the simplest with respect to the cross-sectional shape of the channels (round and infinitely wide rectangular), and then for channels with a more complex cross-sectional shape. To take into account the effect (on the pressure loss) of the channel cross-sectional shape and the presence of a flow with a free surface in it, additional correction factors are introduced (using the hydraulic radius concept) as well as new dependencies and formulas for determining the hydraulic friction coefficient are given, s taking into account the influence of morphometric elements of the channel on the hydraulic resistance of the machine channels of pumping stations.

Aspects of the extension of forty exploitation of bulk reservoirs for irrigation and hydropower purposes

“…Since the supply channel has a high bottom slope, which contributes to the emergence of high flow rates during the passage of the design flow, during the reservoir filling in the channel there will be a suction mode. This will lead to intensive planned and deep deformations and intensive silting of the reservoir bowl due to the product being eroded [2,10,11].…”

“…To solve the mentioned problem in the channel of the supply channel, it was recommended to reconstruct it with the construction of interfacing structures at the interface of the concrete part with the earthen channel in the initial section and in the mouth of the channel with the following scheme and hydraulic parameters [11,12,13,[14][15][16][17][18][19][20][21] (Fig .four).…”

Coastal and deep deformations of the riverbed in the area of a damless water intake

“…The main water intake structure in the a KMC is located on the stable shore of Cape Pulizin with a supply canal 21 kilometers long upstream from the hydropost of the city of Kerki in the Republic of Turkmenistan. The Amudarya River is characterized as a river with a wandering canal [1][2][3]. During water intake from the Amudarya River to the Karshi main canal, difficulties arise due to rapid siltation, sediment deposition of the head section of the canal and erosion of the opposite bank of the river from the water intake point.…”

“…In the course of the Amudarya River, the largest head structures with a damless water intake have been built. These include the head structures: the Amuzang, Jaihun, Karakum, Karshi Main and Amu-Bukhara machine canals [4][5][6][7][8][9]. When water is taken from the river, there is a quantitative and qualitative change in the flow characteristics.…”

Hydraulic resistances experimental and field studies of supply canals and pumping stations structures

“…At present, numerous pumping stations have been created in the irrigation systems of the Republic of Uzbekistan, with the help of which about 50 billion m 3 of water are pumped per year for irrigation of more than 2 million hectares of irrigated land. The most important element of these pumping stations (PS) are water supply and water supply machine canals and structures of pumping stations (PS) [1][2][3][4][5][6][7]. Turning to the question of those engineering problems, in the solution of which the results of this work can be used, let us select, first of all, from the wide range of design cases related to free-flow canals, the main design case, which we will keep in mind in what follows (as, so to speak, " starting ").…”