Characterisation of electric discharge in laminar flow with optical diagnostics

The present work focuses on the interaction between an electric discharge generated by a commercial pencil coil and surrounding air flow in terms of aerodynamics and heat release using advanced optical diagnostics. This investigation is firstly performed with pin-to-pin electrodes in air at rest under atmospheric pressure condition. The velocity of the gas surrounding the spark and the temperature field are measured respectively by Particle Image Velocimetry and Spontaneous Raman Scattering techniques. The time evolution of the current and voltage at the electrodes are monitored for an evaluation of the maximum deposited energy. In a second step, the topology evolution of the discharge in a laminar air flow is investigated for several flow velocities. High-speed intensified imaging technique is used for visualizing the spark interactions with the flow and its changes in growth, shape, and duration. The impacts of the electric discharge on the gas flow are investigated by means of high-resolution phase-locked PIV. The whole results build a database which intends to bring a better understanding of plasma-aerodynamics interactions but also to provide data for ignition models validations.