A combustor with high air preheating and strong internal exhaust gas recirculation is numerically simulated. The combustor operates in the mild combustion mode. characterized by relatively low flame temperatures, low NO, emissions, no visible flame and no sound. The Eulerian Particle Flamelet model by Earths et al. [1] is employed to calculate NO in a postprocessing stage. Predictions of the mean and fluctuating velocity components, as well as local residence times, are compared with experimental data. It is found that the predicted profiles reproduce the data reasonably well, but some discrepancies were found. The NO emission calculated using this unsteady flamelet model is relatively close to measurements available from a previous study, while steady flamelets overpredict the NO emission by an order of magnitude. (C) 2001 by The Combustion Institute.