Electrohydrodynamic Phenomena in Non-Equilibrium Plasmas and Electric Discharges
Abstract
This thesis investigates the complex phenomena of electrohydrodynamic flow (EHD) generated by non-equilibrium plasmas and electric discharges through a series of integrated studies. By employing numerical simulations, and theoretical approaches, this research offers a cohesive exploration into the underlying physics and modeling techniques. This investigation enhances the understanding of EHD phenomena, providing valuable perspectives and strategies in the field. It begins with investigation of the effect of dielectric surface conductivity on the electrical and mechanical characteristics of surface Dielectric Barrier Discharge (DBD) actuators. Two different configurations of surface DBD actuators are explored to control airflow, revealing how the dielectric surface conductivity affects the discharge behavior and flow field by altering EHD force strength, direction, and distribution. The next part introduces a mean model of DBD discharge, designed to efficiently simulate DBD plasma actuators with photoionization considered. This innovation offers a compromise between computational burden and physical accuracy, allowing for a more effective investigation of EHD phenomena. To overcome computational challenges, an artificial damping is incorporated into the electron density equations to hinder discharge pulses and shorten the simulation time. Delving deeper into the nature of pulsed discharges and discharge fronts, a detailed analysis follows, focusing on numerical modeling of non-equilibrium gas discharge plasmas in dry ambient air leading to Trichel pulse discharge. By employing various models validated against experimental data, the study elucidates the impact of gas flow and heating on pulse characteristics. Additionally, a novel DBD plasma actuator is designed for controlling airflow with diverging and converging nozzles. Utilizing the Active Disturbance Rejection Control method, this approach demonstrates robust performance in co-simulation experiments, enriching the understanding of airflow manipulation, more specifically in airflow attenuation and amplification. Finally, the work explores numerical approaches in simulating Trichel pulses generated by multiple interacting discharge systems. This study reveals intriguing self-synchronization phenomena in multi-electrode discharge systems, including the discovery of two distinct synchronization modes and the multi-stable nature of coupled pulsed electric discharges. Collectively, these investigations provide a comprehensive and innovative insight into the physics, modeling, and control of non-equilibrium plasmas and electric discharges, contributing significantly to the field of EHD.