A numerical toolkit for the ignition delay time and ignition probability density predictions based on instantaneous mixing fields in OpenFOAM

Abstract

The OpenFOAM built-in chemistry solver, chemFoam, is extended as multiMeshChemFoam to simultaneously calculate the zero-dimensional (0D) ignition processes on the entire computational domain of practical simulations. The instantaneous temperature, pressure, and species mass fractions of a mixing field are input for the ignition calculation. A solver termed idtFoam is then developed to extract the Ignition Delay Time (IDT) on all cells from the 0D calculations. Several ignition criterions including the temperature exceeds a threshold value, the peaks in heat release rate (or equivalently, the time derivative of temperature) and species mass fractions are available. Another solver denoted as ipdFoam is finally compiled to construct the Ignition Probability Density (IPD) on the entire domain for a certain period. A time series of transient data from the mixing field are necessitated for the ignition calculation, IDT extraction, and IPD construction on individual cells. The numerical toolkit is verified with chemFoam for the 0D ignitions of ethylene. It is then applied to the mixing fields of an ethylene-fueled model supersonic combustor. It is computationally-efficient to evaluate the ignition performance of practical combustion systems in the design phase. Furthermore, assessment on the ignition properties can be made prior to any detailed and computationally-expensive simulations on the reactive flow, since only mixing field is required for calculating the IDT and IPD