ELECTROMAGNETIC FLOW CONTROL: A REVIEW AND EXPERIMENTAL DEVELOPMENT AND TESTING OF A COMPACT ACTUATOR by ERIC M. BRAUN Presented to the Faculty of the Graduate School of The University of Texas at Arlington in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE IN AEROSPACE ENGINEERING THE UNIVERSITY OF TEXAS AT ARLINGTON November 2008 Copyright c by ERIC M. BRAUN 2008 All Rights Reserved In memory of my mother. ACKNOWLEDGEMENTS First and foremost, I would like to thank my mother, Marcia Lee, for all of her support of my education. Unfortunately, she passed away suddenly while recov- ering from inflammatory breast cancer (IBC) treatment shortly before I was able to complete this thesis. Finances were always difficult as she raised me and my sister, Lisa, but she sacrificed a great deal and somehow managed to assist in paying for our education including graduate school. I wanted to attend graduate school at a university that would give me the ability to pursue various research interests and projects. In light of that statement, I am very grateful to the three professors I have worked for while at the UT Arlington Aerody- namics Research Center. Dr. Frank Lu and Dr. Don Wilson have been tremendously supportive since the day I arrived. I believe their research advice and graduate level courses have instilled just as much knowledge in me as I could receive at any highly ranked university. Dr. Craig Dutton, despite moving on to the University of Illinois at Urbana-Champaign in 2007, has continued to assist me with my research project. I am also thankful to Dr. Kamesh Subbarao for serving as a committee member for this thesis. I additionally wish to thank Dr. Ramakanth Munipalli of HyPerComp, Inc., for providing a computational MHD code that has been used for the EMFC electric field calculations presented in this paper. This work was partially supported by the Texas Advanced Research Program, Project No. 003656-0013-2006. Since 2006, I am glad to have worked with fellow researchers Richard Mitchell, Adam Pierce, and Akihiro Nozawa as well as Rod Duke, our scientific apparatus engineering technician, on rebuilding the low-speed and supersonic wind tunnels at iv the ARC. Between these large efforts and many smaller ones, I think we have been able to considerably improve the ARC for future research efforts. Additionally, they have all assisted me at some point with the research presented in this thesis. I have enjoyed working on a collaborative research project with Professor Yung-Hwan Byun and Hui Jeong from Konkuk University. I have also had the privilege of a great working environment at the ARC with an ever-increasing amount of people, notably including Rafaela Bellini, Albert Ortiz, Dr. Philip Panicker, and Prashaanth Ravindran, all of whom I have known for over two years now along with those mentioned in the beginning of this paragraph. November 25, 2008 v ABSTRACT ELECTROMAGNETIC FLOW CONTROL: A REVIEW AND EXPERIMENTAL DEVELOPMENT AND TESTING OF A COMPACT ACTUATOR ERIC M. BRAUN, M.S. The University of Texas at Arlington, 2008 Co-Supervising Professors: Frank K. Lu and Donald R. Wilson This thesis is divided into two sections which both relate to the field of mag- netohydrodynamics and particularly electromagnetic flow control (EMFC). The first section contains a review of recent research in EMFC. The second section presents the experimental results of a compact EMFC actuator designed for use at low speeds where the flow conductivity is raised by conductive seed particle injection. Fifty years ago, publications began to discuss the possibilities of using EMFC to improve aerodynamic performance. This led to an era of research that focused on cou- pling the fundamentals of magnetohydrodynamics (MHD) with propulsion, control, and power generation systems. Unfortunately, very few designs made it past an ex- perimental phase as, among other issues, power consumption was unreasonably high. Recent proposed advancements in technology like the MARIAH hypersonic wind tun- nel and the AJAX scramjet engine have led to a new phase of MHD research in the aerospace industry, with many interdisciplinary applications. Aside from propulsion systems and channel flow accelerators, electromagnetic flow control concepts applied to control surface aerodynamics have not seen the same level of advancement that vi may eventually produce a device that can be integrated with an aircraft or missile. Therefore, the purpose of this thesis is to review the overall feasibility of the different electric and electromagnetic flow control concepts. Emphasis is placed on EMFC and experimental work. The second section describes the development and testing of a facility for elec- tromagnetic boundary layer flow control employing conductive particle seeding. It was designed and constructed to perform basic research in EMFC and address some of the issues discussed in the review. The facility consists of three integrated com- ponents: a conductive particle seeding system, an ionization actuator, and a Lorentz force actuator. The Lorentz force actuator was designed in particular to be compact, employing a row of flush-mounted surface electrodes alternated with embedded Nd- FeB magnets perpendicular to the flow direction. Experiments were performed in a low-speed wind tunnel with atmospheric pressure. Low ionization energy potassium carbonate particles were meant to be seeded into the airflow to then be ionized by a high voltage field before passing over the active EMFC actuator. Although a high voltage field can ionize air and create a glow discharge, the potassium carbonate seed is largely unaffected. It appears that the potassium carbonate seed must be broken down thermally or with a high voltage, high current pulse that contains energy at the level needed to vaporize the potassium carbonate molecules. Different forms of seed- ing were attempted but were largely unsuccessful. A glow discharge was established over the EMFC actuator, but PIV imaging indicates that the boundary layer effects produced in this case were largely a result of Joule heating and not the Lorentz force. In the conclusion, several recommendations are laid forth pertaining to the future of EMFC experimentation with compact actuators and conductive particle seeding. vii TABLE OF CONTENTS ACKNOWLEDGEMENTS . iv ABSTRACT . vi LIST OF FIGURES . xi LIST OF TABLES . xvi NOMENCLATURE . xvii Chapter 1. INTRODUCTION . 1 1.1 Introduction . 1 1.2 Fundamental MHD Theory for Aerodynamics . 3 2. MHD INTERACTION . 8 2.1 Overview . 8 2.2 EMFC Actuator Characterization . 13 2.2.1 Electric and Electromagnetic Force Comparison . 13 2.2.2 Scaling Parameters . 16 3. CRITICAL ISSUES IN EMFC ACTUATOR DESIGN . 25 3.1 Channel Flow and Open Flow Experimentation . 25 3.2 Power Consumption and Packaging . 31 3.3 Selection of EMFC Magnets . 34 3.4 Conductivity . 37 3.5 Overall Feasibility . 44 4. ELECTRIC FIELD CONTROL AND REVIEW CONCLUSIONS . 49 4.1 Flow Control by Glow Discharge . 49 viii 4.2 Flow Control by Dielectric Barrier Discharge . 54 4.3 Conclusions and Future Outlook . 61 5. LOW SPEED EMFC FACILITY DESIGN . 67 5.1 Overview and Experimental Objectives . 67 5.2 Conductive Particle Seeding . 70 5.2.1 Dry Particle Selection . 70 5.2.2 Seeding System . 72 5.3 Ionization System . 74 5.4 Compact Lorentz Force Actuator . 76 5.4.1 Conceptual Design . 76 5.4.2 Optimization . 78 5.4.3 Characterization and Magnetic Field Mapping . 82 5.4.4 Scaling Parameters . 85 6. BENCH TESTING OF EMFC SYSTEMS . 92 6.1 Ionization System Performance . 92 6.2 Salt Water EMFC . 94 7. LOW SPEED WIND TUNNEL TESTING . 98 7.1 Flat Plate Boundary Layer PIV Survery . 98 7.2 Survey of Seeding Systems . 102 7.3 Attempts at EMFC while Ionizing Seed Particles . 105 7.3.1 Conductive Particle Substitution . 107 7.4 Attempts at EMFC with an Aqueous Salt Spray . 109 7.5 Glow Discharge EMFC Actuator . 109 7.5.1 Accelerating Force Results . 110 7.5.2 Retarding Force Results . 114 7.5.3 Comparison of Results . 117 ix 8. CONCLUSIONS . 120 8.1 Feasibility of Particle Seeding . 121 8.2 Feasibility of a Compact Actuator . 124 Appendix A. LORENTZ FORCE POWER SUPPLY DESIGN . 126 REFERENCES . 131 BIOGRAPHICAL STATEMENT . 147 x LIST OF FIGURES Figure Page 2.1 Image of the five electrode, four magnet actuator plate with dielectric material shown as transparent . 19 2.2 Total magnetic field located on the surface of the flat plate over the 10:8 × 3:2 cm area . 20 2.3 The common logarithm of the Lorentz force (N/m2) across a spanwise slice over the actuator at x = 1.8 cm . 21 2.4 The common logarithm of IM =L across a spanwise slice over the actuator at x = 1.8 cm . 21 2.5 The common logarithm of IEM =L across a spanwise slice over the actuator at x = 1.8 cm . 22 3.1 Normalized static pressure traces downstream of an EMFC actuator for M = 3 dry air for four electromagnetic arrangements (from [1]) . 30 3.2 Boundary layer velocity profile downstream of a flat plate EMFC actuator for salt water flow (from [2]) . 31 3.3 Smoke visualization of a DBD control surface composed of rows of actuators creating an electrostatic force that acts from left to right (from [3]) . 32 3.4 A water-cooled electromagnet surrounds an EMFC free jet test section (from [4]) . 33 3.5 Temperature versus Mach number for lines of constant wedge angle (1◦, 5◦, 10◦, 20◦) after an oblique shock wave (based on an initial temperature of 220 K) along with Neodymium and Samarium-Cobalt maximum operating temperatures . 37 3.6 Magnetic flux density charted as a function of the maximum operating temperature for several Neodymium and Samarium-Cobalt alloys [5] . 38 3.7 A typical plot of the surface field decline versus temperature for a Neodymium magnet with a maximum operating temperature of xi 423 K [6] .