NUMERICAL METHOD OF CALCULATION OF AN AXISYMMETRIC TURBULENT JETS OF REACTING GASES IN THE DIFFUSIVE COMBUSTION BASED ON THE MODIFIED TURBULENCE MODEL

This article examines the mixing and combustion of reacting gases in turbulent jets flowing out of a round nozzle and propagating in a cocurrent airflow. The considered physical process is described by the system of differential equations of turbulent boundary layer of multicomponent reacting gas. On the basis of the similarity of convective and turbulent transport of individual components, a single stoichiometric equation of the chemical reaction is constructed, where generalized “fuel”, “air” and “reaction product” are involved. With the introduction of the Schwab-Zeldovich and relative-excess concentration functions and the use of a single stoichiometric equation, the three conservation equations of the “generalized” components are reduced to a single equation. Formulas for determining the concentration of components, temperature, density, flame front and other thermophysical parameters of the complex heat and mass transfer process depending on the initial data and the local value of the relative-excess concentration and total enthalpy are constructed. The problem is solved numerically using a two-layer, four-point, implicit finitedifference scheme and a simple run. The iterative process was used due to the nonlinearity of the equations of conservation and transport of substances and the unknown boundary of the jet. Some mathematical models of turbulence are analyzed. A modification of the second model of Prandtl by turbulence is proposed and the values of the empirical constants included in this model for different compositions of the combustible mixture are determined. The main results of the computational experiment are presented in the form of graphs and the corresponding conclusions are drawn.