Abstract. The article considers the modeling of aeration of water masses by water jets falling on the surface in order to improve the quality of water from surface water sources. The mechanism of the aeration process is described when a turbulent non-crushed jet falls onto the water surface. Calculated analytical and experimental studies of air entrapment by cylindrical jets falling into the water made at the Department of Hydraulics of MSUCE made it possible to obtain a universal dimensionless dependence, suitable for describing the process of air entrapment in various conditions. The results of experimental verification of this dependence are presented, as well as the results of simulation of air entrainment in specific conditions of the collector chamber when its sections are mated to a large level difference. The results of mathematical simulation of the release of air-gas inclusions from the water flow at the lower part of the collector are presented. The volumetric flow rate of the air-gas mixture in the collector below the collector chamber is identified. Estimated calculation of the parameters of the deaeration of the water flow: the length, time and the rate of ascent of air bubbles, is executed.1 The justification of the calculated dependences on the identification of air entrapment at large differences and mathematical modeling of the capture of the air-gas mixture in the collector chamberIn the development of engineering measures for improving of the quality of water from surface water sources, improving of the water quality in urban water bodies, improving of the efficiency of the use of settling ponds for cleaning up of contaminated surface runoff and industrial wastewater, an artificial aeration of water masses is used [1], [2]. Aerators, perturbing the surface of the stream, serve as an artificial turbulence promoter of the water mass, therefore, for the known perturbation parameters initiated by the aerator on the free surface, physical modeling of this process must be considered taking into account the hydrodynamic features. The dimensions and power of the aeration devices are different, but the accuracy of their hydroaerodynamic calculations based mostly on laboratory experimental data is currently insufficient

It has been found that air entrainment occurs when the average jet velocity at the plunging point reaches a certain value. This velocity is called the critical velocity of air entrainment. The analysis of studies in this field shows that the process of jet interaction with the liquid surface is complex, while the theoretical approaches to its description are insufficient. The conditions at which air entrainment begins are related to the behavior and shape of the meniscus. The mechanism of meniscus formation is based on the complicated kinematic structure of motion in the vicinity of the point of interaction between the jet and the liquid in the quiescent state. Experiments and observations show that the meniscus behavior is closely related to the initial conditions of air entrainment. Calculating the critical velocity of air entrainment Ue, analysis of the meniscus shape, and use of the limit equilibrium condition were used to derive a new criterion relationship for the air entrainment conditions of turbulent jets flowing from long smooth nozzles. The results of calculations are compared with experimental data.