The study of the discharge influence on mixing of gaseous fuel jet with the supersonic air flow

The paper presents the results of numerical simulation of the effect of a long spark discharge on the mixing dynamics of an injected gas jet with supersonic air flow. The calculations were performed using the CFD soft-ware package FlowVision. The fuel was supplied using an injector located on the channel wall, and the discharge was organized near the wall downstream of the injector. Simulation of electrical spark discharge was performed using a volumetric heat source. In order to describe the principal specifications of a plasma actuator to accelerate mixing in a supersonic flow (Mach number M = 2), the research involved varying the energy impact to the discharge in the range of 100–500 mJ per pulse, determining the influence of the shape and location of the discharge. A study of the fuel injection modes in a supersonic air flow has been carried out and an optimal gas jet outflow regime has been found to study the effect of a spark discharge. A method has been developed for analyzing the disturbance pattern of the fuel–oxidant interface caused by the operation of a pulsed spark discharge. A program was prepared in the LabView software environment for obtaining quantitative characteristics for further comparison with the results obtained in the experiment.
The simulation results allow us to conclude that the long spark discharge located along the flow downstream of the injector provides the maximum increase in the interface between the jet of fuel and the main flow. A typical repetition frequency of discharge pulses in a pulse-periodic mode should be more than 6 kHz with a discharge length of $\sim10$ mm to ensure a continuous effect on the mixing at a flow velocity of 500 m/s.