Study of autoignition of natural gas in diesel environments using computational fluid dynamics with detailed chemical kinetics

In this work, fluid flow and detailed chemical kinetic calculations were combined as a step along the way to understand the ignition process of natural gas (NG) in diesel environments. The kinetic scheme consisted of 31 species in 125 reactions. The flow calculations involved time-dependent, fully elliptic Navier-Stokes equations, and conservation equations of mixture mass, mass of 31 species, and energy. The simulations were done for a constant volume cylindrical chamber filled initially with air at high temperature (>1000 Ii) and pressure (25.2 atm) into which the cold natural gas was injected. The computations were confined to the near field of the jet assuming laminar, axisymmetric flow. Initial air temperature and chamber height were varied in this study. The computations revealed that the fluid dynamics affected the ignition delay and location of the ignition spot. Computed results from this work are consistent with experimental data on autoignition of NG in diesel environments. (C) 1998 by The Combustion Institute.