Capture of Air by a Water Stream at Coupling of Sites of a Non-Pressure Collector with a Large Level Difference

Abstract

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

Evaluating the critical velocity of air entrainment by plunging water jets

“…Experiments show [7][8][9] that at small jet velocities, no air is entrained. In this case, the jet enters the receiving liquid as a rigid rod, as shown in the photo in Fig.…”