Computational and Experimental Study of NOx Formation in Hydrogen-Fueled Pulse Detonation Engines

Abstract

The formation of NOx in hydrogen-fueled pulse detonation engines (PDE) is investigated numerically and experimentally. 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 were in good agreement with experimental measurements obtained at two operating frequencies and two equivalence ratios. Additional computations studied in detail the effects of equivalence ratio and residence time on NOx formation at ambient conditions. The results indicate that NOx formation in PDEs is minimized by operating with lean or rich mixtures, and by utilizing the shortest possible detonation tubes. NOx emissions for very lean or very rich mixtures are fairly insensitive to residence time. Operation of the PDE at near stoichiometric equivalence ratios results in very high NOx levels. However, the NOx emission parameter decreases greatly for lean or rich mixtures reaching values comparable to those obtained with current gas turbine engines.