Numerical Investigation on a Cavity-Based Scramjet Model: Lessons Learnt and Challenges

The scramjet engine has been identified as one of the most promising propulsion systems for hypersonic vehicles. The flow in the scramjet remains supersonic with a typical residence time of 1 millisecond. Short time scales and the coupling of multiple physics yield a complex flow field in which the flame kernels morph into a reacting vortex ring upon interaction with the supersonic flow, making mixing enhancement, ignition, and flame stabilization major challenges in the development of scramjet engines.

A cavity-based scramjet model was designed and a test facility was built accordingly at Technion-Israel Institute of Technology. Meanwhile, the simulation strategy of the scramjet model was set up using a hybrid RANS/LES method based OpenFOAM, which is an open source CFD toolbox. Both experimental and numerical efforts have been made to investigate the combustion characteristics in the scramjet. In this talk, the complementary results of both approaches will be presented to explore the rich physics in the flow field of the scramjet. We propose a new method to divide the flow field into different regions and decompose the combustion into different modes by using filter functions. The focus is placed on the links among the fuel injection schemes, flame stabilization locations, combustion modes, and vorticity transport behaviors in the scramjet. The lessons we’ve learnt and challenges we’re facing will be summarized