Dr. Konstantinos Kiousis | University of West Attica / Πανεπιστήμιο Δυτικής Αττικής (original) (raw)

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Papers by Dr. Konstantinos Kiousis

The ionic wind which is generated in the space between the emitter and the collector electrode of... more The ionic wind which is generated in the space between the emitter and the collector electrode of a wire-cylinder air gap, under high voltage DC application, has been experimentally and theoretically analyzed from an electro hydrodynamic (EHD) standpoint. A theoretical analysis has been carried out based on the model that ions interact with the surrounding medium, thus creating a neutral air molecule flow. Experiments have been conducted in order to determine the relationship between the electric corona discharge current, the ionic wind velocity and the applied high voltage, as well as their dependence on geometrical characteristics of the electrodes. The investigation has shown that the ionic wind velocity is an approximately linear function of the applied voltage and is proportional to the square root of the discharge current, with a very good agreement of the experimental results with theoretical data. Parametric analysis showed that increased electrode gap reduces the wind veloc...

This paper presents the parametric study of an EHD air pump based on a single needle to grid elec... more This paper presents the parametric study of an EHD air pump based on a single needle to grid electrode geometry, particularly intended for active cooling applications. The parametric study examines the effect on the overall performance of the EHD pumps which the distance between the emitter/collector electrodes has on this specific design, as well as the radius of the collector grid wire. For this purpose, EHD pump prototypes have been fabricated and their performance is being investigated through laboratory experiments. The experiments also displayed that this very simple and low cost design is capable of producing viable practical results, depending on the application.

The electric field distribution in a wire-cylinder electrode arrangement in air, under high volta... more The electric field distribution in a wire-cylinder electrode arrangement in air, under high voltage dc application, has been studied by implementing the Finite Element Analysis (FEA). The applied mesh parameters have been optimized in terms of accuracy and processing power. Numerical analysis has been carried out on the field intensity, along the wire-cylinder gap axis, considering different geometrical characteristics of the electrodes, which play an important role in the spatial distribution of the electric field. The maximum field intensity was mainly associated to the wire-cylinder radii ratio, while the distance between the electrodes strongly affected the distribution along the axis of the gap. On the other hand, the potential distribution was almost independent of the gap length.

Lecture Notes in Electrical Engineering, 2014

The inception voltage of the positive corona discharges (CIV) in a typical wire-cylinder electrod... more The inception voltage of the positive corona discharges (CIV) in a typical wire-cylinder electrode arrangement in air, under high voltage dc application, has been studied by implementing the Finite Element Analysis (FEA). Numerical analysis has been carried out on the electric field intensity, along the wire-cylinder gap axis, in order to determine the inception voltage of each air gap and define its dependence on geometrical characteristics of the electrodes. An experimental investigation has been conducted and used so as to justify the simulation results. The CIV was mainly associated to the wire radius, while the distance between the electrodes had a secondary importance. Finally, the inception voltage had slight changes for different cylinder radii.

DEDICATION iii ACKNOWLEDGEMENTS iv DECLARATION STATEMENT v TABLE OF CONTENTS 1 LIST OF TABLES 3 L... more DEDICATION iii ACKNOWLEDGEMENTS iv DECLARATION STATEMENT v TABLE OF CONTENTS 1 LIST OF TABLES 3 LIST OF FIGURES 5 GLOSSARY 12 LIST OF PUBLICATIONS 16 CHAPTER 1 INTRODUCTION 18 1.1 THE EHD EFFECT APPLICATIONS 18 1.2 RESEARCH OBJECTIVES 24 1.3 METHODOLOGY 25 1.4 OUTLINE OF THE THESIS 27 CHAPTER 2 THEORETICAL ASPECTS 29 2.1 ELECTRIC FIELD 29 Electric field distribution 30 2.2 CORONA DISCHARGE 34 Coefficient A 37 Coefficient k 38 2.3 UNIPOLAR SATURATION CURRENT 38 2.4 CURRENT DENSITY DISTRIBUTION 40 2.5 IONIC WIND 41 Flow Limitation 43 2.6 GENERATED THRUST 44 2 CHAPTER 3 EXPERIMENT 47 3.1 ELECTRODE GEOMETRY 47 3.2 FEA MODEL 49 Governing Equations 50 FEA Modelling Parameters 51 Verification of the mesh formation 56 3.3 EXPERIMENTAL SETUP 57 CHAPTER 4 FEA SIMULATION RESULTS AND DISCUSSION 60 4.1 PROPOSED FORMULA FOR EMAX IN THE CASE OF WIRE-CYLINDER ELECTRODE ARRANGEMENT 66 4.2 FEA FIELD LINE LENGTHS 69 4.3 SATURATION CURRENT DENSITY LIMIT 73 4.4 UNIPOLAR SATURATION CURRENT LIMIT 75 CHAPT...

A parametric study of a single needle-to-grid EHD air pump, intended for semiconductor cooling ap... more A parametric study of a single needle-to-grid EHD air pump, intended for semiconductor cooling applications, is being presented in this paper. The effect of the distance between the emitter and collector electrodes, as well as the radius of the collector's grid wires, is being examined. To that end, several experimental EHD pump prototypes have been fabricated and their performance has been investigated. The experiments demonstrate that this simple and low-cost design is capable of producing usable results, depending on the space and voltage restrictions of the application, for emitter to collector distances greater than 15 mm.

International Journal of Power and Energy Systems, 2014

IEEE Transactions on Dielectrics and Electrical Insulation, 2014

ABSTRACT This paper presents a model for the determination of the ionic unipolar corona saturatio... more ABSTRACT This paper presents a model for the determination of the ionic unipolar corona saturation current in parallel wire-cylinder electrodes in the air, based on the geometrical characteristics of the electric field lines distributing in the space surrounding the electrodes, under high voltage dc application. The distribution of the lengths of the electric field lines connecting the electrodes is determined by finite element analysis. Then the acquired data are treated theoretically in order to calculate the total saturation unipolar corona current limit for the aforementioned electrode arrangement. Experimental investigation has shown that corona current is closely related to the unipolar saturation current limits derived from the proposed model.

Plasma Science and Technology, 2014

ABSTRACT This paper presents the design, optimization and fabrication of an EHD air pump intended... more ABSTRACT This paper presents the design, optimization and fabrication of an EHD air pump intended for high-power electronic chip cooling applications. Suitable high-voltage electrode con- figurations were selected and studied, in terms of the characteristics of the generated electric field, which play an important role in ionic wind flow. For this purpose, dedicated software is used to implement finite element analysis. Critical design parameters, such as the electric field intensity, wind velocity, current flow and power consumption are investigated. Two different laboratory prototypes are fabricated and their performances experimentally assessed. This procedure leads to the fabrication of a final prototype, which is then tested as a replacement of a typical fan for cooling a high power density electronic chip. To assist towards that end, an experimental ther- mal testing setup is designed and constructed to simulate the size of a personal computer’s CPU core of variable power. The parametric study leads to the fabrication of experimental single-stage EHD pumps, the optimal design of which is capable of delivering an air flow of 51 CFM with an operating voltage of 10.5 kV. Finally, the theoretical and experimental results are evaluated and potential applications are proposed.

Plasma Science and Technology, 2014

The electric field distribution in an air gap between a wire-cylinder electrode configuration, ha... more The electric field distribution in an air gap between a wire-cylinder electrode configuration, has been studied by implementing Finite Element Analysis. The electrodes were assumed to be surrounded by air at normal conditions, while high dc voltage has been applied across them, with positive polarity at the wire. Numerical analysis on the maximum electric field intensity along the wire-cylinder gap axis, as well as on the potential distribution in the air surrounding the electrodes has been carried out, considering different geometrical characteristics of the electrodes. The applied mesh parameters were optimized, in terms of accuracy and processing power. The maximum field intensity was mainly associated with the wire radius r and the electrode gap length d. The cylindrical electrode radius R had a limited impact on the maximum electric field intensity but, on the other hand, it had a strong effect in the distribution of the electric field lines. Finally, a formula for the estimation of the maximum electric field intensity is proposed.

The ionic wind which is generated in the space between the emitter and the collector electrode of... more The ionic wind which is generated in the space between the emitter and the collector electrode of a wire-cylinder air gap, under high voltage DC application, has been experimentally and theoretically analyzed from an electro hydrodynamic (EHD) standpoint. A theoretical analysis has been carried out based on the model that ions interact with the surrounding medium, thus creating a neutral air molecule flow. Experiments have been conducted in order to determine the relationship between the electric corona discharge current, the ionic wind velocity and the applied high voltage, as well as their dependence on geometrical characteristics of the electrodes. The investigation has shown that the ionic wind velocity is an approximately linear function of the applied voltage and is proportional to the square root of the discharge current, with a very good agreement of the experimental results with theoretical data. Parametric analysis showed that increased electrode gap reduces the wind veloc...

This paper presents the parametric study of an EHD air pump based on a single needle to grid elec... more This paper presents the parametric study of an EHD air pump based on a single needle to grid electrode geometry, particularly intended for active cooling applications. The parametric study examines the effect on the overall performance of the EHD pumps which the distance between the emitter/collector electrodes has on this specific design, as well as the radius of the collector grid wire. For this purpose, EHD pump prototypes have been fabricated and their performance is being investigated through laboratory experiments. The experiments also displayed that this very simple and low cost design is capable of producing viable practical results, depending on the application.

The electric field distribution in a wire-cylinder electrode arrangement in air, under high volta... more The electric field distribution in a wire-cylinder electrode arrangement in air, under high voltage dc application, has been studied by implementing the Finite Element Analysis (FEA). The applied mesh parameters have been optimized in terms of accuracy and processing power. Numerical analysis has been carried out on the field intensity, along the wire-cylinder gap axis, considering different geometrical characteristics of the electrodes, which play an important role in the spatial distribution of the electric field. The maximum field intensity was mainly associated to the wire-cylinder radii ratio, while the distance between the electrodes strongly affected the distribution along the axis of the gap. On the other hand, the potential distribution was almost independent of the gap length.

Lecture Notes in Electrical Engineering, 2014

The inception voltage of the positive corona discharges (CIV) in a typical wire-cylinder electrod... more The inception voltage of the positive corona discharges (CIV) in a typical wire-cylinder electrode arrangement in air, under high voltage dc application, has been studied by implementing the Finite Element Analysis (FEA). Numerical analysis has been carried out on the electric field intensity, along the wire-cylinder gap axis, in order to determine the inception voltage of each air gap and define its dependence on geometrical characteristics of the electrodes. An experimental investigation has been conducted and used so as to justify the simulation results. The CIV was mainly associated to the wire radius, while the distance between the electrodes had a secondary importance. Finally, the inception voltage had slight changes for different cylinder radii.

DEDICATION iii ACKNOWLEDGEMENTS iv DECLARATION STATEMENT v TABLE OF CONTENTS 1 LIST OF TABLES 3 L... more DEDICATION iii ACKNOWLEDGEMENTS iv DECLARATION STATEMENT v TABLE OF CONTENTS 1 LIST OF TABLES 3 LIST OF FIGURES 5 GLOSSARY 12 LIST OF PUBLICATIONS 16 CHAPTER 1 INTRODUCTION 18 1.1 THE EHD EFFECT APPLICATIONS 18 1.2 RESEARCH OBJECTIVES 24 1.3 METHODOLOGY 25 1.4 OUTLINE OF THE THESIS 27 CHAPTER 2 THEORETICAL ASPECTS 29 2.1 ELECTRIC FIELD 29 Electric field distribution 30 2.2 CORONA DISCHARGE 34 Coefficient A 37 Coefficient k 38 2.3 UNIPOLAR SATURATION CURRENT 38 2.4 CURRENT DENSITY DISTRIBUTION 40 2.5 IONIC WIND 41 Flow Limitation 43 2.6 GENERATED THRUST 44 2 CHAPTER 3 EXPERIMENT 47 3.1 ELECTRODE GEOMETRY 47 3.2 FEA MODEL 49 Governing Equations 50 FEA Modelling Parameters 51 Verification of the mesh formation 56 3.3 EXPERIMENTAL SETUP 57 CHAPTER 4 FEA SIMULATION RESULTS AND DISCUSSION 60 4.1 PROPOSED FORMULA FOR EMAX IN THE CASE OF WIRE-CYLINDER ELECTRODE ARRANGEMENT 66 4.2 FEA FIELD LINE LENGTHS 69 4.3 SATURATION CURRENT DENSITY LIMIT 73 4.4 UNIPOLAR SATURATION CURRENT LIMIT 75 CHAPT...

A parametric study of a single needle-to-grid EHD air pump, intended for semiconductor cooling ap... more A parametric study of a single needle-to-grid EHD air pump, intended for semiconductor cooling applications, is being presented in this paper. The effect of the distance between the emitter and collector electrodes, as well as the radius of the collector's grid wires, is being examined. To that end, several experimental EHD pump prototypes have been fabricated and their performance has been investigated. The experiments demonstrate that this simple and low-cost design is capable of producing usable results, depending on the space and voltage restrictions of the application, for emitter to collector distances greater than 15 mm.

International Journal of Power and Energy Systems, 2014

IEEE Transactions on Dielectrics and Electrical Insulation, 2014

ABSTRACT This paper presents a model for the determination of the ionic unipolar corona saturatio... more ABSTRACT This paper presents a model for the determination of the ionic unipolar corona saturation current in parallel wire-cylinder electrodes in the air, based on the geometrical characteristics of the electric field lines distributing in the space surrounding the electrodes, under high voltage dc application. The distribution of the lengths of the electric field lines connecting the electrodes is determined by finite element analysis. Then the acquired data are treated theoretically in order to calculate the total saturation unipolar corona current limit for the aforementioned electrode arrangement. Experimental investigation has shown that corona current is closely related to the unipolar saturation current limits derived from the proposed model.

Plasma Science and Technology, 2014

ABSTRACT This paper presents the design, optimization and fabrication of an EHD air pump intended... more ABSTRACT This paper presents the design, optimization and fabrication of an EHD air pump intended for high-power electronic chip cooling applications. Suitable high-voltage electrode con- figurations were selected and studied, in terms of the characteristics of the generated electric field, which play an important role in ionic wind flow. For this purpose, dedicated software is used to implement finite element analysis. Critical design parameters, such as the electric field intensity, wind velocity, current flow and power consumption are investigated. Two different laboratory prototypes are fabricated and their performances experimentally assessed. This procedure leads to the fabrication of a final prototype, which is then tested as a replacement of a typical fan for cooling a high power density electronic chip. To assist towards that end, an experimental ther- mal testing setup is designed and constructed to simulate the size of a personal computer’s CPU core of variable power. The parametric study leads to the fabrication of experimental single-stage EHD pumps, the optimal design of which is capable of delivering an air flow of 51 CFM with an operating voltage of 10.5 kV. Finally, the theoretical and experimental results are evaluated and potential applications are proposed.

Plasma Science and Technology, 2014

The electric field distribution in an air gap between a wire-cylinder electrode configuration, ha... more The electric field distribution in an air gap between a wire-cylinder electrode configuration, has been studied by implementing Finite Element Analysis. The electrodes were assumed to be surrounded by air at normal conditions, while high dc voltage has been applied across them, with positive polarity at the wire. Numerical analysis on the maximum electric field intensity along the wire-cylinder gap axis, as well as on the potential distribution in the air surrounding the electrodes has been carried out, considering different geometrical characteristics of the electrodes. The applied mesh parameters were optimized, in terms of accuracy and processing power. The maximum field intensity was mainly associated with the wire radius r and the electrode gap length d. The cylindrical electrode radius R had a limited impact on the maximum electric field intensity but, on the other hand, it had a strong effect in the distribution of the electric field lines. Finally, a formula for the estimation of the maximum electric field intensity is proposed.