Transverse jet mixing based on energy deposition control via pulsed discharge

Improving the mixing efficiency of wall-normal jets in supersonic flows is crucial for enhancing combustion efficiency and conserving fuel. Pulse discharge energy deposition has been shown to be an effective method for enhancing mixing of transverse jets. The study investigates the structure of transverse jets and the effectiveness of control methods influenced by the momentum flux ratio. Experiments were carried out in a wind tunnel with an incoming flow Mach number of 2.47, focusing on how upstream plasma energy deposition arrays could improve the mixing of downstream transverse jets. Employing high-speed schlieren and planar laser scattering techniques, the research unveiled the impact of high-frequency energy deposition on the flow field structural characteristics of single-hole jet injection and the effects of single-pulse energy deposition on double-hole jet injection. Furthermore, the fluctuation and spectral characteristics of the flow field were elucidated using time-resolved schlieren image-based root mean square and fast Fourier transform methods. The evolution mechanism of transverse jets under high-frequency discharge was probed using the Spectral Proper Orthogonal Decomposition (SPOD) technology. The findings indicate that pulse discharge energy deposition can generate “energetic eddies,” which substantially altered the jet structure. These eddies diminished the bow shock wave, decreased the low-frequency oscillations of the shock wave, and created super-largescale wake vortices that are in sync with the discharge frequency within the jet plume. This resulted in a significant improvement in the penetration depth and spanwise width of the jet near the wall. When the energetic vortex interacted with the downstream bow shock, secondary reinforcement occurs. It is also demonstrated that high-frequency energy deposition markedly boosted the fluctuation intensity of the jet. As the momentum flux ratio increased, the disturbance capability of energy deposition was enhanced, and the range of disturbance also expanded.