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Purpose: to develop a methodology for calculating jet devices used in hydromechanization for the development of soils and cleaning reservoirs from sediments using the results of our own research and the theoretical and empirical dependences presented in the literature. Materials and Methods: on the example of a diagram of an annular two-surface jet ejectors with increased energy characteristics, a method has been developed and the calculation of the relative and actual geometric and hydraulic parameters of its elements is shown for use as a suction tip on suction dredgers at the necessity to increase the suction height and development depth of centrifugal dredgers. Results. Based on the initial data (the values of the hydraulic resistance coefficients of the inlet section, diffuser, nozzle, the distance from the nozzle edge to the beginning of the mixing chamber, mixer, operating parameters of the pump – pump head and flow rate, pipeline diameters), the pulp density in the suction nozzle, the weight coefficient of ejection, geometric characteristic, relative optimum head, actual heads of the jet apparatus and pump-blower, volumetric total flow, volumetric consistency of the pulp in the suction pipeline, performance over the ground, actual dimensions. Conclusions: the developed methodology will allow calculating the optimal dimensions of jet enjector of a new design and developing a design for the suction tip of a suction dredger for various in pressure, flow rate and development depth of operational options for removing bottom sediments in water bodies.

Purpose: theoretical substantiation of the method for calculating the total energy in suction and pressure pipelines of the main units at reclamation pumping stations to prevent unsteady processes and water hammer. Materials and methods: research and calculations were carried out at the pumping station “Mezhdurechye”, “Management of Stavropolmeliovodkhoz”, equipped with three main centrifugal pump units and two pressure pipelines. To calculate the total energy in the suction and pressure pipelines of the main pump, the entire pipeline network is divided into three sections: the first one is the intake, the second one is the distribution and the third one is the main pressure pipeline. For each section from 0.25 to 3.41 с²/м⁵ and the entire network 4.65 с²/м⁵, specific resistances were determined, the actual total head losses from 2.50 to 29.32 m when three units were fed into two pressure pipelines from 0.3 to 7.2 m³/s and hydraulic parameters of each unit: head (90.2 m), flow (2.67 m³/s), power (1585 kW), admissible vacuum suction head (4.2 m) at efficiency (88 %), with various operating options of the pumping station. Results: as a result of the research, the procedure for determining the total energy in the suction and pressure pipelines of the main units at reclamation pumping stations was determined, the total energy was calculated depending on the number of running pumping units: for suction pipelines from plus 0.1 to minus 1.5 m, for pressure pipelines from 75.79 to 86.34 m, which allows calculating the required hydraulic parameters of the booster pump used to close the back flow valve in the pressure pipelines of the main pump, to prevent backflow of water and water hammer before stopping the main pump. Conclusions: the above method is recommended for calculating in case of necessity the prevention of water hammer in the network by closing the back flow valve with a booster pump for reclamation stations equipped with centrifugal pumps with a maximum possible head of 120–130 m, in a complex operational option – the maximum number of pumps per one pipeline.