Ignition of a cold hydrogen jet in a coaxial hot vitiated air flow expanding into a still space
O.S. Vankova1, N.N. Fedorova1
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: hydrogen combustion, modeling, internal flows, flame stabilization
Abstract
Results of a numerical study of ignition of a cold supersonic (Мjet = 1.46) hydrogen jet surrounded by an annular supersonic (Mair = 1.86) jet of hot vitiated air expanding into a submerged space are reported. The simulations are performed under the experimental conditions of Cohen and Guile (1969) based on the Reynolds-averaged Navier-Stokes equations supplemented with the k-w SST turbulence model, a detailed kinetic mechanism of hydrogen combustion in air, and various models for taking into account the turbulence-chemistry interaction. The calculations are performed in the ANSYS Fluent 2020 R1 software in a transient two-dimensional axisymmetric approach by using a pressure-based solver. The instantaneous, mean, and RMS components of the main aerodynamic parameters and species mass fractions are obtained. A detailed comparison of the calculated profiles of the Mach number, total temperature, and species mass fractions along the jet axis and in several jet cross sections for non-reacting and reacting flows with experimental data is performed, revealing reasonable agreement in all parameters. It is demonstrated that the use of the transient approach combined with a detailed kinetic scheme makes it possible to reproduce the vortex structures developing at the combustion layer boundary, which make a significant contribution to hydrogen-air mixing, and, thus, affect the hydrogen combustion process.
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