This paper is directed towards understanding how composition of the coal transport medium (primary CO2 and O2) affects the observed ignition stand-off distance in 40 kW co-axial turbulent diffusion, oxy-coal flames, supported in a specially designed combustion test rig, rated at 100 kW. First, a methodology to define and quantify the observed ignition stand-off distance in laboratory combustor ...

A large eddy simulation (LES)/probability density function (PDF) method is proposed for modeling turbulent spray combustion. The PDF method has the advantage that the chemical source term appears closed but requires models for the small scale mixing process. The transport equation for the joint-scalar PDF is high dimensional and solved using a Lagrangian technique. A stable and consistent numer...

A premixed turbulent combustion Direct Numerical Simulation (DNS) database of a swirl burner is analyzed from three angles: estimation of the three-dimensional flame surface from two-dimensional fields; modeling of subgrid source and flux terms entering the balance equation for the reaction progress variable in Large Eddy Simulation (LES); and modeling of the subgrid-scale scalar variance in LE...

We report a large-eddy simulation (LES)/probability density function (PDF) modeling study of a turbulent lifted ethylene jet flame in a heated air coflow, using a 22-species reduced chemical mechanism. In this flame, the central ethylene jet is ignited by the heated coflow, and the lifted jet flame base stabilization reaches a statistically stationary state. In this LES/PDF study, the filtered ...

The origins of autoignition at hot spots are analysed and the pressure pulses that arise from them are related to knock in gasoline engines and to developing detonations in ducts. In controlled autoignition engines, autoignition is benign with little knock. There are several modes of autoignition and the existence of an operational peninsula, within which detonations can develop at a hot spot, ...

Methods of using stochastic simulations to treat nonlinear interactions in turbulent combustion processes are described emphasizing the use of statistical time-series techniques to analyze the turbulence-radiation interactions of nonpremixed flames. Three aspects of the problem are considered, as follows: the statistics of scalar properties in turbulent flames, the formulation of algorithms to ...