Two approaches to calculating composition of rarefied gas mixture exposed to chemical reactions at flow through cylindrical channel

Abstract

Two approaches to calculating the change in the composition of a rarefied gas mixture due to gas-phase and heterogeneous reactions when it flows through a heated cylindrical channel into a vacuum are considered. The first approach is based on the direct simulation Monte Carlo (DSMC) method taking into account gas-phase reactions. The second one consists in combining the DSMC method without gas-phase reactions and the solving of chemical kinetics equations for taking into account gas-phase reactions. An analysis of the approaches is carried out on the example of the hydrogen and methane mixture flow through a heated tungsten channel. The study was conducted for different ratios of the channel length to its diameter, different coefficients of accommodation, and in a wide range of gas rarefaction degrees: from free molecular to transitional regimes. The developed methods provide a possibility of solving similar problems for non-equilibrium flows. The obtained results may be useful for optimization of gas-dynamic sources, based on thin tubes.