Mixing enhancement of strut based flame stabilizer for scramjet combustor using passive techniques

In a Supersonic combustion ramjet (Scramjet) engine, the combustion occurs at supersonic velocity as the incoming air remains supersonic. In the scramjet combustor, the mixing and combustion should take place within a few milliseconds. The effect of passive techniques to enhance the mixing characteristics is examined. Two wedges are used downstream of the strut injection to either enhance the mixing due to shock or introduce strong vortices. The first configuration can be named dummy struts (DS) and the second configuration as inverted dummy struts (IDS). The former configuration enhances mixing due to shock and expansion fans, while the latter enhances mixing due to strong recirculation. Improved delayed detached eddy simulation (IDDES) is a hybrid RANS/LES method used in the current simulation. The validated result of the single strut is compared with the DS and IDS configurations. It is found that the placement of DS plays a vital role. The mixing enhancement was more in IDS, followed by DS. The acoustics characteristics show IDS has the highest noise generation. Dynamic Mode Decomposition (DMD) sheds light on the dominant frequency and corresponding characteristics of waves.