Thesis Format

Integrated Article

Electrohydrodynamic Phenomena in Non-Equilibrium Plasmas and Electric Discharges

Author

Afshin Shaygani, Western UniversityFollow

Degree

Doctor of Philosophy

Program

Electrical and Computer Engineering

Supervisor

Kazimierz Adamiak

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.

Summary for Lay Audience

This thesis delves deeply into the realm of electrohydrodynamic flow (EHD), employing advanced scientific computation through extensive computer modeling and simulation. It meticulously examines the interactions between electric currents and fluids within plasma environments. Central to this study is the investigation of electric discharges, alongside the development of efficient computational models to simulate these phenomena. Furthermore, the research explores the synchronization phenomena within multiple discharge systems, uncovering unique collective behaviors. This work significantly advances our understanding of EHD and plasma, as well as their computational modeling, and opens up potential applications in the development of electric propulsion systems for spacecraft and in advancing clean fusion energy research.

Recommended Citation

Shaygani, Afshin, "Electrohydrodynamic Phenomena in Non-Equilibrium Plasmas and Electric Discharges" (2023). Electronic Thesis and Dissertation Repository. 9777.
https://ir.lib.uwo.ca/etd/9777