Effect of confinement in high-speed reacting mixing layer

Abstract

High Mach number mixing layers play an important role in the development of supersonic combustor ramjet (scramjet) engines. The mixing of air and fuel is hindered by both shorter combustor residence time and by stability of supersonic shear layer relative to subsonic counterpart. Although many experimental and computational investigations were carried out for supersonic free shear layer [1, 2, 3, 4 and 5] and confined shear layer [6, 7, 8 and 9], the effect of lateral confinement on supersonic mixing layer is not clearly brought out. The fundamental difference in the development of turbulence in the mixing layer and wall boundary layer can affect the structure of the flow and the growth rate of mixing layer significantly. Chakraborty et al. [9] have performed two-dimensional direct numerical simulation (DNS) for high-speed confined reacting shear layer with finite rate chemical kinetics with seven species and seven reactions. Arguments have been provided for treating two-dimensional calculation using the work of Lu and Wu [8], Zhuang et al. [10], Farouk et al. [7], and others who have conducted computational study of the compressibility of high-speed mixing layer and shown that two-dimensional simulation is satisfactory for confined mixing layer. Good comparison of experimental wall pressure distribution with DNS results obtained was considered the basis of further investigations.