The article discusses various types of new improved dam water intake hydroelectric systems, sedimentation facilities, sediment control devices on rivers and canals with a rational layout. The results of the analysis of studies on the use of the theory of transverse circulation and methods of artificial, active regulation of the structure of the water intake flow are presented, which has become widespread in world practice and is the main one for creating an effective design of water intake headworks for pumping stations and hydropower facilities that provide them with reliable protection from sediments. The author of the article, on the basis of numerous experimental data obtained in various countries of the world, makes a conclusion about the effectiveness and prospects of using front-type structures with more than 50% water intake. The design of water intakes of this type has been significantly improved; they can be successfully used in various conditions, including on Mountain Rivers. The author draws attention to the development of a new design of the pioneer ditch, which ensures the efficient passage of bottom sediments into the downstream of the structure, which prevents intensive silting of the reservoir basin by bottom sediments and improves the efficiency of the dam water intake.
A mathematical model of the unsteady uneven movement of the river flow in the area of the damless water intake, flowing in deformable channels, was developed and numerically implemented. In the developed model of the deformation of the river channel, flowing on easily eroded beds, adapted formulas of the transporting ability of the flow are used, the hydrodynamic equations of motion and continuity of the flow, deformation of the channel, and sediment balance. To close the system of differential equations, we use the adapted formula of the conveying ability of the flow–Benold. In the calculations, the non-erosion speed was taken according to the formula C.E. Mirtschulava, taking into account standard values of adaptive coefficients. It is suitable for describing deformation processes, taking into account the drift of dredging slots. The model contains the minimum number of equations and empirical constants. In the present work, a numerical model is proposed for predicting channel processes in river beds in the area of damless water intakes and is verified on the results of experimental studies. The figures show sequential deformations of the channel, arising due to natural causes, as well as due to channel adjustment and treatment works (discharge of soil from the supply channel into the river). As can be seen from these figures, the channel from multi-sleeve is gradually turning into one-sleeve. It has been established that after 1 year of observation at low water, as a result of discharge of sediment from the sewage treatment works, the river ducts die off. These ducts are observed only in the flood. Note that below the Karshi main channel (KMCh), the left bank eroded by about 150 m. After a 10-year course, the low-water course turned into a one-arm riverbed. As a result of the erosion of the left-bank islands, it turned into the river itself. During the flood, there are also no pronounced sleeves, a significant erosion of the left bank is noted, up to 700 m. After that, this bank was strengthened. In the future, the channel process did not undergo significant changes. Towards the end of the 10th year of observation, the channel broadened somewhat, and the flood depth decreased in the flood. Comparison of the results of field and numerical studies shows that the developed model gives good results. For low-water conditions, coincidence is better than for flood conditions. During the flood, under natural conditions, somewhat greater depths are observed on the floodplain than in the calculations. It should be noted that both in calculations and in kind: - there was a significant erosion of the left bank below the KMCh; - the channel of the Amudarya river in the considered section from multi-sleeve turned into practically one-sleeve.
A mathematical model is presented, a hydraulic jump that appears during the transition of the flow from a turbulent state (Fr>1.0) to critical (Fr<1.0). The main assumptions made to obtain the divergent form of the Saint-Venant hydrodynamic equations are given: - planned (two-dimensional) effects do not affect the flow (but still local energy losses due to sharp turns and changes in the channel shape in the plan can be taken into account; to take into account such losses in local sections of the channel increased local hydraulic resistance is introduced). The results of numerical studies of the downstream of the culvert structure of the medium-pressure reservoir are presented. The developed numerical model using explicit difference schemes is presented. Based on the results of numerical studies of the hydraulic jump, the possibility of establishing the degree of quenching of the excess flow energy having the destructive ability of the construction of the downstream of medium-pressure reservoirs is substantiated. The calculation results showed that an increase in the hydraulic resistance value promotes the displacement of the hydraulic jump against the current and an increase in its associated depths. At the concatenation site of the upstream, there was a sharp decrease in the Froude number from 2.76 to 0.69, with a change in average speed from 8.81 m/s to 3.26 m/s. It is substantiated that from the calculated values of the vertical dimensions of the hydraulic jump with various values of hydraulic resistance and the throughput of the structure, it is possible to determine the horizontal dimensions of the jump, which makes it possible to select the optimal sizes of the downstream attachment zone in and after the hydraulic jump.
For multi-section drainage facilities, it is important to develop operational measures based on maneuvering moving barriers. Maneuvering of moving barriers is a measure that carries out the flow of water from the upper reaches to the lower reaches at the required level, taking into accounts the design features and operational mode of the hydraulic regime of the drainage structure. The maneuvering mode in the flow of water from the discharge structures ensures the order of opening, phasing, and level of opening of these movable barriers. Hydraulic conditions are associated with the effective control of the hydraulic regime in the lower part of the drainage structure or the suppression of excess kinetic energy, the reversal of the flow, or the prevention of post-riser deformation processes. Creating conditions ensuring that the hydrotechnical and hydropower construction of the water transfer or discharge facility is adapted for use in conjunction with a hydropower plant, water intake, sluices, and flow control system.
The article is devoted to solving the problems of reducing the useful volume of bulk reservoirs, which is an urgent task of water management. The development of the design allows to reduce the volume of incoming sediment into the reservoir thicket is the main goal of the present work. The analysis of materials of field studies and a review of existing scientific works was the basis of the research method. The results of field studies on the study of channel processes in the downstream of the feeder channel of a low-pressure reservoir and the dynamics of their siltation. It has been established that the reservoirs accumulate only 0.3-10% of the annual river flow and the degree of annual silting of the capacity of such reservoirs is on average 0.5-2.0%. After 25-50 years, reservoirs may lose half of their usable capacity and after 40-80 years, a complete failure of operation is possible. To slow down this process in the basins of the self-leveling reservoirs, a new structure of structures developed, which ensures an even flow of water in the supply channel and maximum sedimentation of sediments in the channel, which prevents them from entering the reservoir bowl.
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