Determination of ejection coefficient of liquid-gas ejector with combined mixing chamber

Introduction. The aim of the research was to develop a method for determining the actual ejection coefficient of a liquid-gas ejector with a combined mixing chamber. Materials and methods. Theoretical calculation methods were used (balance equations of mass and energy in the form of the Bernoulli equation and the laws of hydrodynamics), experimental methods (ejection coefficients of an ejector with a combined mixing chamber were experimentally determined on a hydraulic bench in order to determine the experimental constant). The Sokolov-Zinger graph-analytical method was used to compare the ejection coefficients. Results and discussions. A characteristic feature of the ejector with a combined mixing chamber is the presence of the initial conical and subsequent cylindrical parts of the mixing chamber. The angle of opening of the conical part is 3-8 degrees less than the angle of the flame of spraying liquid from the nozzle. Such a design reduces the hydraulic resistance to the entry of liquid and prevents the formation of back-circulation flows. The ejection coefficient of a jet device with a combined mixing chamber is by 15-55% higher than that of an ejector with a cylindrical mixing chamber. The joint solution of the balance equations for the conical and cylindrical parts of the mixing chamber, taking into account the energy losses in each, makes it possible to determine theoretical flow rates of the phases in the ejector for different operating modes. The coefficient k takes into account the influence of energy redistribution between phases during ejection and the design of the mixing chamber. When the pressure increases from 0.05 to 0.25 MPa coefficient k increases from 3.6 to 4.8 in a rational exponent function. The effective ejection coefficient is defined as the product of the theoretical ejection coefficient and the experimental constant, while the error does not exceed 5%. Conclusions. The proposed calculation method allows you to determine the effective ejection coefficient of a liquid-gas ejector with a combined mixing chamber.