Large eddy simulation of flame and thermal-acoustic characteristics in a strut-based scramjet with dynamic thickened flame model

Supersonic combustion is a complex phenomenon with multi-physical coupling, and the thermal acoustic coupling under supersonic inflow is also a matter of concern. In this work, Large Eddy Simulation of a strut-stabilized model scramjet is performed with dynamic thickened flame combustion model, and an efficiency function accounting for both, wrinkling loss due to flame thickening and turbulence/flame interaction. The finite-rate chemistry model and a skeletal hydrogen reaction mechanism with 9 species and 27 reactions are adopted. The method allows to predict the complex physical in supersonic reactive flow efficiently and the results are in good agreement with experimental. A comprehensive analysis of the Damko center dot hler number, modified flame index and heat release rate is conducted to investigate the flame structure under shock waves condition, and the difference between heat release rate and reaction rate distributions in Mach number space is also observed. The oscillation characteristics in the strut-based scramjet is discussed mode by mode using the Proper Orthogonal Decomposition approach, and the results identify a mode at 4.997 kHz, in which the thermal-acoustic coupling found, while the stronger modes are the results of multiple factors, including auto-ignition, vortexes shedding and the resulting shock-waves oscillation.