Modeling of Ignition and Combustion of a Coflowing Hydrogen Jet in a Supersonic Air Flow

Results of a numerical study of mixing, ignition, and combustion of a cold hydrogen jet propagating along the lower wall of a channel parallel to a supersonic (M = 2) flow of an inert gas mixture/humid hot air are reported. The computations are performed with the use of the ANSYS CFD Fluent commercial software by means of solving transient Favre-averaged Navier-Stokes equations supplemented with the k-. SST turbulence model and several kinetic schemes of hydrogen combustion. Two single-step schemes and three detailed kinetic schemes including 16, 38, and 37 forward and backward reactions are considered. The goal of the study is to choose a computation method and kinetic mechanism that ensure good agreement with experimental data on supersonic combustion of a coflowing hydrogen jet. In the case of a non-reacting flow, it is demonstrated that the computational algorithm can accurately predict the parameters of mixing of the hydrogen jet and external flow. In the case of a reacting flow, the flow characteristics are significantly affected by large vortex structures developing at the interface between the combustion layer and the external flow. If the flow unsteadiness is taken into account and a detailed kinetic scheme with 37 reactions is used, good agreement of the mean characteristics of the flow with experimental data on the distributions of pressure, temperature, Mach number, and species concentrations at the combustor exit is provided.