Computational study of NOx formation in hydrogen-fuelled pulse detonation engines

The formation of NOx in hydrogen-fuelled pulse detonation engines (PDE) is investigated numerically. The computations are based on the axisymmetric Euler equations and a detailed combustion model consisting of 12 species and 27 reactions. A multi-level, dynamically adaptive grid is utilized, in order to resolve the structure of the detonation front. Computed NO concentrations are in good agreement with experimental measurements obtained at two operating frequencies and two equivalence ratios. Additional computations examine the effects of equivalence ratio and residence time on NOx formation at ambient conditions. The results indicate that NOx formation in PDEs is very high for near stoichiometric mixtures. NOx reduction requires use of lean or rich mixtures and the shortest possible detonation tube. NOx emissions for very lean or very rich mixtures are, however, fairly insensitive to residence time.