Numerical simulation of laminar premixed hydrogen-air flame/shock interaction in semi-closed channel

Abstract

Highly refined simulations of flame/shock interactions (FSI) are performed and analyzed in the context of hydrogen/air combustion in a two-dimensional shock-tube configuration (height 7 cm). The chemical mechanism used for the hydrogen oxidation contains 9 reactive species, without nitrogen oxides, and 23 kinetic reactions. An initially planar laminar premixed flame (ϕ = 0.8, P=20 kPa) is left to evolve until the ratio between its burning flame velocity and the laminar flame speed reaches 1.45. Two thermal wall boundary conditions are envisaged: isothermal with Twall fixed to 300 K and adiabatic. The species transport is described with a unity Lewis number for all species or by complex transport. Once the flame is established, a shock is installed in the domain which propagates toward the flame. Two values of the Mach number for the incident shock are considered: Ms=1.4 and Ms=1.9. The relative impacts of the wall thermal condition, of the species transport modeling and of the incident shock Mach number on the FSI process are discussed. It is observed that thermal boundary conditions and transport modeling have a weak impact during the first stages of the FSI, i.e. the two successive interactions of the incoming and reflected shock with the flame, but a significant one once the reflected shock has crossed the flame front.