One-dimensional Numerical Model of Transient Discharges in Air of a Spatial Plasma Ignition Device by Florin N. Saceleanu A thesis submitted to the Faculty of Graduate and Postdoctoral Affairs in partial fulfillment of the requirements for the degree of Master of Applied Science in Mechanical and Aerospace Engineering Carleton University Ottawa, Ontario ©2013, Florin N. 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The author retains copyright L'auteur conserve la propriete du droit d'auteur ownership and moral rights in this et des droits moraux qui protege cette these. Ni thesis. Neither the thesis nor la these ni des extraits substantiels de celle-ci substantial extracts from it may be ne doivent etre imprimes ou autrement printed or otherwise reproduced reproduits sans son autorisation. without the author's permission. In compliance with the Canadian Conformement a la loi canadienne sur la Privacy Act some supporting forms protection de la vie privee, quelques may have been removed from this formulaires secondaires ont ete enleves de thesis. cette these. While these forms may be included Bien que ces formulaires aient inclus dans in the document page count, their la pagination, il n'y aura aucun contenu removal does not represent any loss manquant. of content from the thesis. Canada Abstract This thesis examines the modes of discharge of a plasma ignition device. Oscilloscope data of the discharge voltage and current are analyzed for various pressures in air at ambient temperature. It is determined that the discharge operates in 2 modes: a glow discharge and a postulated streamer discharge. Subsequently, a 1-dimensional fluid simulation of plasma using the finite volume method (FVM) is developed to gain insight into the particle kinetics. Transient results of the simulation agree with theories of electric discharges; however, quasi-steady state results were not reached due to high diffusion time of ions in air. Next, an ordinary differential equation (ODE) is derived to understand the discharge transition. Simulated results were used to estimate the voltage waveform, which describes the ODE’s forcing function; additional simulated results were used to estimate the discharge current and the ODE’s non-linearity. It is found that the ODE’s non-linearity increases exponentially for capacitive discharges. It is postulated that the non-linearity defines the mode transition observed experimentally. The research is motivated by Spatial Plasma Discharge Ignition (SPDI), an innovative ignition system postulated to increase combustion efficiency in automobile engines for up to 9%. The research thus far can only hypothesize SPDI’s benefits on combustion, based on the literature review and the modes of discharge. Acknowledgements I would like to thank my supervisor, Dr. Ronald Miller, for giving me the opportunity, guidance and financial support to complete this thesis. I would also like to thank Mr. Glen Clarke and Dr. Alex Plotnikov, from Sphenic Technologies Inc., for providing a SPDI device and financial support for this research. In particular, I am grateful to Dr. Tanvir Farouk, from University of South Carolina, for the discussions and guidelines regarding plasma modeling. I would also like to acknowledge my family for their encouragement and additional financial support whenever necessary. Table of Contents Abstract.............................................................................................................................. ii Acknowledgements .......................................................................................................... iii Table of Contents..............................................................................................................iv List of Tables......................................................................................................................x List of Figures ................................................................................................................... xi List of Appendices............................................................................................................xv Nomenclature................................................................................................................. xvi 1 Chapter: Introduction.................................................................................................1 1.1 Spatial Plasma Discharge Ignition (SPDI) ...........................................................................1 1.2 Motivation for SPDI ...............................................................................................................3 1.3 Scope of the Thesis.................................................................................................................3 1.4 Outline .....................................................................................................................................4 • Background information ........................................................................................................4 • Literature review ....................................................................................................................4 • Analysis of SPDI experiments and relevant assumptions ..................................................4 • Modeling the SPDI discharge ................................................................................................5 • Results and discussion ........................................................................................................... 5 • Conclusions and future work .................................................................................................5 2 Chapter: Plasma Fundamentals................................................................................ 6 2.1 Definition of Plasma .............................................................................................................. 6 2.2 Fundamental Plasma Parameters .......................................................................................... 6 2.3 Plasma Types.......................................................................................................................... 8 2.4 Plasma in Industry ..................................................................................................................9 2.5 Parameters Describing Plasma Behavior ............................................................................ 10 2.5.1 Particle collisions and the effect of electric field ...........................................................10 2.5.2 Free and ambipolar diffusion..........................................................................................12 2.5.3 Degree of quasi-neutrality and boundary surface interaction ......................................13 3 Chapter: Thermodynamics and Kinetics in Plasma...............................................15 3.1 Overview of Statistical Thermodynamics .......................................................................... 15 3.2 The Internal Energies of Diatomic Molecules ....................................................................16 3.3 Fundamental Collisions ........................................................................................................16 3.3.1 Internal excitation .............................................................................................................17 3.3.2 Direct impact ionization .................................................................................................. 17 3.3.3 Penning ionization ............................................................................................................18 3.3.4 Photo-ionization ...............................................................................................................18 3.3.5 Electron attachment ..........................................................................................................18 3.3.6 Detachment.......................................................................................................................19 3.3.7 Recombination .................................................................................................................19 3.4 Kinetics Applicable to Plasma ............................................................................................. 19 3.4.1 Boltzmann kinetic equation ............................................................................................. 19 3.4.2 Maxwellian VDF ..............................................................................................................20