Numerical investigation of the effect of rotation on non-premixed hydrogen combustion in developing turbulent mixing layers

This study was aimed at examining the influence of the system rotation as an external action on the development of vortical structures and combustion. Specifically, three-dimensional direct numerical simulations of compressible mixing layers with non-premixed /air combustion were performed using a detailed chemical reaction scheme. The relationship between the developing vortical structures and chemical reactions in the flow field with the rotation was investigated. The development of combustion changed depending on the vortical structures, and the presence of roller vortices promoted the combustion phenomena. The influence of the vortical structures on the elementary reactions, which contribute to the heat release rate, was small. During the anticyclonic rotation, the roller vortices collapsed and suppressed the combustion. In contrast, the cyclonic rotation resulted in the generation of quasi-2D roller vortices, which enlarged the high-heat-release-rate regions and promoted the combustion. Overall, the vortical structures induced by the rotation can change the development of combustion even though the elementary reactions that contribute to the heat release rate remain unchanged. The presented findings can guide the prediction and control of turbulent combustion in practical situations involving fluid machinery.