Investigations On Mixing Enhancement And Flame Holding Characteristics Of Ramp Injector In Supersonic Flow

Nanoparticle-based Planar Laser Imaging (NPLI) method and other advanced flow visualization techniques, as well as numerical methods, are applied to in-depth investigations of mixing enhancement and flame holding characteristics of ramp injector in supersonic flow.Mixing characteristics of ramp injectors with different configurations are investigated in non-reaction flows. Major factors that contribute to the mixing effects are analysed. It's indicated that the blending effect of stream-wise vortexes behind the ramp is the main mechanic of ramp mixing enhancement. Expansion ramps perform better in mixing than compression ramps. Sweepback configuration is beneficial to strengthen the stream-wise vortexes, which intensify the mixing effect accordingly. Reflected shock waves in the flow field interact with the jet plume, which implicate two types of mixing enhancement mechanics.The ignition process, combustion and flow characteristics and flame holding effects of ramp injector are explored in reaction flows. Results reveal that self-ignition is inclinable to occur in the expansion ramp, and two auto ignition mechanics are employed. Flow structure alters intensely in ignition process, which results in remarkable differences between flow structures of reaction and cold flow. The recirculation zone formed at bottom of the flow behind the ramp holds flame effectively.Flow field and mixing characteristics of aerodynamic ramp are studied in cold flows. Experimental and numerical results show that aero-ramp generates stream-wise vortexes downstream jet orifices by blocking and lifting the incoming flow, which intensifies mixing. The dominant mechanic of mixing enhancement alters along with injection pressure. By employing fractal dimension measurements, aero-ramp is proved to perform better in far-field mixing than physical ramp.