Numerical Study of the Conversion of Methane Mixtures under the Influence of Laser Radiation

-The article presents a study of the laser conversion of methane mixtures under various conditions of the computational experiment. Such flows are characterized by sharp local changes in the gas dynamic characteristics and concentrations of the mixture components. Their dynamics and mutual transformations are described by a rigid system of Navier-Stokes equations and chemical kinetics, which imposes serious restrictions on the choice of computational algorithm. Numerical experiments are carried out using previously developed 2D code for modeling subsonic axisymmetric flows of a multicomponent medium, supplemented by moduli that take into account laser radiation and solve the equations of the chemical kinetics of methane conversion. The accuracy of the results is checked by calculating the conversion of methane under the influence of external heating of the walls. Comparison of the concentrations of the substances at the pipe outlet with the direct solution of the chemical kinetics system at different reaction temperatures shows a good agreement of the results. Computational experiments on the effect of laser radiation on the flow of a chemically active absorbing medium are completed. It is shown that the laser radiation introduced into the mixture and absorbed by ethylene changes the flow pattern and significantly increases the temperature of the gas mixture. An increase in temperature contributes to an increase in the yield of the target products (ethylene, acetylene, and hydrogen) at shorter length of the reactor, while in the absence of radiation the maximum concentrations of products appear at the reactor outlet. The effect of the initial composition of the gas mixture on the methane conversion is investigated, and it is concluded that the presence of ethylene significantly increases the formation of target products at moderate temperatures of the reactor walls in the presence of laser radiation.