DNS predictions of NOx production in developing turbulent mixing layers with non-premixed hydrogen–air combustion

ABSTRACT Direct numerical simulations of three-dimensional compressible mixing layers with non-premixed hydrogen–air combustion were performed using a detailed chemical reaction mechanism with production. Flow fields with three types of initial disturbances were simulated to investigate the relationship between developing vortical structures and formation. The amounts of and produced in the simple shear layer were smaller than those in the two- and three-dimensional mixing layers with vortical structures. In the mixing layers, the formation and expansion of the combustion region by the roller vortices and the baroclinic torque had a significant impact on production, while the relatively low-temperature combustion region formed by the three-dimensional developed rib vortices in the blade regions between the roller vortices had a large effect on the production. It was found that a two-dimensional simulation can estimate the production, while the information on a three-dimensional mixing layer is necessary to predict the production.