Numerical investigations were conducted to analyze the coupling effects of pulsed H2 jets and nanosecond-pulsed actuation (NS-SDBD) in a supersonic crossflow. The FVM was employed to solve the multi-component 2D URANS equations with the SST k-omega turbulence model, while H2-air combustion was described using a seven species–seven reactions chain reaction model, and the plasma thermal effect was represented by a phenomenological model. The backward-facing step flows with an inlet Mach number of 2.5 and a pulsed jet frequency of 10 kHz under different actuation conditions were simulated. The combustion enhancement mechanism under an actuation frequency of 20 kHz was analyzed. Research indicates that compression waves induced by NS-SDBD enhance H2-air mixing and facilitate temperature transport as the flow progresses. This progress is significantly associated with the flow structures generated by pulsed jets. Under this condition, the fuel utilization rate in the flow field increased by 61.2%, the total pressure recovery coefficient increased by 5.34%, and the outlet total temperature slightly increased even with a 50% reduction in fuel flow rate. Comparative analysis of different actuation cases demonstrates that evenly distributed actuation within the jet cycle yields better effects. The innovation of this study lies in proposing and exploring a potential method to address inadequate combustion under high-speed inflow conditions, which couples NS-SDBD with pulsed hydrogen jets.
Read full abstract