Flame Dynamics and Chemistry in LRE Combustion Instability

Nonpremixed jet flames have been extensively studied to understand the combustion processes in rocket engines. The stabilization and structure of jet flames determine the lift-off height of the flame and are therefore integral to engine design. In view of the nonpremixed nature of the fuel and oxidizer jets, there are two dominant modes of flame stabilization. The traditional view is that mixing between the two jets will eventually lead to a region of strong reactivity and hence auto-ignition. An alternate view, advanced recently and for largely non-autoignitive situations, is stabilization through the so-called tribrachial flame also known as triple flame, in which a lean and a rich premixed flame wing with a trailing diffusion flame branch. The point where the three branches intersect, the triple point, is considered to be the stabilization point. The dynamic balance between the local flame propagation speed and the incoming flow speed is the stabilization mechanism.