Numerical Simulation of Turbulent Hydrogen Combustion Regimes Near the Lean Limit

Abstract

A problem formulation is proposed for simulating lean premixed hydrogen–air combustion in a closed volume with numerically generated turbulence. Two-dimensional simulations of flame propagation from a small ignition kernel showed that the following sequence of regimes is observed with increasing turbulence intensity and decreasing mixture strength: a corrugated flame with a continuously connected front, a regime with a local loss of front connectivity, and flame extinction through disintegration of a growing kernel into fragments. The transition from steady self-sustained combustion to extinction corresponds to changes in mixture and turbulence parameters leading to a stronger influence of turbulent velocity field on local flame structure. The proposed approach to numerical simulation of the transition regime characterized by loss of front connectivity and fragmentation of the flame under the action of turbulent eddies can be used to evaluate the effect of turbulence intensity on flammability limits.