Mechanism of a transverse jet mixing enhanced by high-frequency plasma energy deposition

Abstract

The mixing mechanism of a transverse jet enhanced by high-frequency plasma energy deposition is investigated at Ma = 6.13 using both experimental measurements and improved delayed detached eddy simulation. The test configuration is a flat plate with argon gas injected vertically at its center. The plasma actuator driven by 20 and 50 kHz pulsed discharge is used as a mixing enhancement device, which is located upstream of the jet. The schlieren and planar laser scattering visualization show that the interaction between the hot bubbles induced by the plasma energy deposition and the bow shock caused by the jet generates large scale vortices that diffuse the jet components, and improve the penetration depth of the jet. These large-scale vortices augment the vorticity and turbulence intensity, thus enhancing the jet component mixing. The vortex analysis indicated that the jet vorticity increases due to the stronger baroclinic torque induced by Richtmyer–Meshkov (R–M) instability around the bubble/shock interaction region, which promotes the turbulent kinetic energy and the production of the large-scale vortex structures. The baroclinic torque and the resulting large-scale vortices are the physical origin of the enhanced mixing of the transverse jet.