Negative Drag Coefficient in Electrostatic Pendulum

ORAL

Abstract

This paper focuses on the force produced by corona, the electrohydrodynamic (EHD) effect (``ion wind''). In recent years, the EHD effect has been investigated for purposes of aerodynamic drag reduction. We present a simple experiment involving an electrostatic pendulum that demonstrates ``negative drag''. When a thin suspension wire of a ball-bearing pendulum is raised to a high enough DC potential to produce corona, positive feedback is established between the ion wind produced by the corona and the direction of air currents around the wire. This positive feedback produces an effective negative drag that adds mechanical energy to the system and causes the pendulum amplitude to increase approximately exponentially over a period as long as four minutes. In this paper we quantify the net negative drag on the system and propose a qualitative theory as to why negative drag is produced.

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Authors

  • Jose Hernandez

    Texas State University

  • Qiye Zheng

    Santa Fe Institute, Baylor University, University of Texas at Dallas, Department of Chemistry, The University of Texas at Austin, Jozef Stefan Institute, Texas A&M University-Commerce, Commerce, Texas 75429, Cyclotron Institute, Texas A&M University, College Station, Texas 77843, Texas A&M University, Department of Physics, Texas State University, Department of Physics, Baylor University, University of Texas at El Paso, Univ of Texas, El Paso, University of Science and Technology of China, The University of Texas at Dallas, Faculty, None, Southwestern University, Texas State University, Texas A&M University - Commerce, UT Southwestern Medical Center, National High Magnetic Field Laboratory, The Cyclotron Institute at Texas A&M University, Department of Biological Sciences, Texas State Univ-San Marcos, The University of Texas at Dallas, Richardson, Texas 75080, King Abdullah University of Science and Technology, Univ of Texas, Dallas, N.Chiao Tung U., UT Dallas, Inorganic Chemistry and Catalysis Group, Utrecht University, Electrical & Computer Engineering, Baylor University, Department of Materials Science and NanoEngineering, Rice University, University of Texas at Arlington, University of Chicago, The University of Mississippi, Astronomical Observatory, Warsaw University, Nicolaus Copernicus Astronomical Centre, Polish Academy of Sciences, Rochester Institute of Technology, California Institute of Technology, University of Houston, NASA-GSFC and UMBC, MD, Virginia Tech, VA, Texas Christian University, The University of Texas at San Antonio, Department of Physics, Teivecca Nazarene University, Weatherford College, Air Force Research Laboratory, Sensors Directorate, WPAFB, OH, USA, Air Force Research Laboratory, Directed Energy Directorate, KAFB, NM, US, Department of Physics & Astronomy, University of Texas at San Antonio TX, USA, University of Arizona, University of North Carolina at Chapel Hill, Stanford University, Harvard Center for Astrophysics, Texas A\&M University, UTSW, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, Boston College, Chestnut Hill, Massachusetts 02467, Naval Research Laboratory, Washington, D.C. 20375