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Publication Title | Aerodynamic Control Using Windward-Surface Plasma Actuators on a Separation Ramp

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JOURNAL OF AIRCRAFT
Vol. 44,
No. 6, November–December 2007
Aerodynamic Control Using Windward-Surface Plasma Actuators on a Separation Ramp
Javier Lopera∗ and T. Terry Ng†
University of Toledo, Toledo, Ohio 43606
Mehul P. Patel,‡ Srikanth Vasudevan,§ and Ed Santavicca¶ Orbital Research Inc., Cleveland, Ohio 44103
and
Thomas C. Corke∗∗
University of Notre Dame, Notre Dame, Indiana 46556
DOI: 10.2514/1.30741
Wind-tunnel experiments were conducted on a 47-deg sweep, scaled 1303 unmanned air vehicle model to assess the performance of an innovative windward-surface plasma actuator design for flight control at low angles of attack. Control was implemented by altering the flow past an aft separation ramp on the windward side using a single dielectric barrier discharge plasma actuator. The influence of ramp-expansion angles (20, 30, and 40 deg) on the plasma actuator’s ability to affect flow separation and aerodynamic lift was examined. Both steady and unsteady actuations of the plasma actuator were examined, and their effects were captured using lift measurements and flow visualizations. Results reveal that the plasma actuator effects are highly dependent on the ramp angle and actuator parameters such as duty cycle and modulation frequency. The actuators produced significant shifts in the lift curve, up to 25% for the most effective ramp angles of 20 and 30 deg, in the 0–20-deg 􏰃 range. Flow visualization results confirmed that the plasma actuator causes the flow to reattach over a region downstream of the separation ramp. For all ramp cases examined, the unsteady (pulsed) actuator was more effective than the steady actuator in controlling flow separation and influencing the aerodynamic lift. The aerodynamic effect of plasma actuators was found to be highly dependent on the ramp angle and the separation strength over the ramp. Significant control forces were obtained using windward-surface plasma actuators and, indirectly, these control forces can be implemented to generate substantial control moments for maneuvering air vehicles.
􏰃 = CL = c = F􏰄 = fmod = I = Lsep = P = Rec =
Nomenclature
angle of attack, deg
lift coefficient
wing chord
nondimensional frequency of actuator frequency of modulation, Hz
current, A
streamwise extent of the separation zone, m power, W
chord Reynolds number
Strouhal number
freestream velocity, m=s
voltage, V
phase angle between current and voltage in an ac circuit, rad
I. Introduction
THERE has been an increased interest in recent years in
expanding the functions of unmanned air vehicles (UAVs) for both civilian and military operations. Technologies that enable revolutionary capabilities in augmenting the performance of UAVs are being developed worldwide. One such technology is active flow control (AFC). AFC offers methodologies that can expand the flight envelope of UAVs, improve their aerostructural performance, and also free up the design space from the constraints of traditional aerodynamic control systems. This paper discusses an innovative active flow control approach involving a windward-surface single dielectric barrier discharge (SDBD) plasma actuator as a flow control device for providing lift and pitch control on a 1303 UAV configuration. Earlier work by Patel et al. [1] focused on lift enhancement at high angles of attack through leading-edge vortex control using plasma actuators. The present study investigates lift control at low angles of attack using a plasma actuator at the lip of a backward-facing separation ramp on the windward surface near the trailing edge. This paper presents experimental evidence of the control effectiveness of a windward-ramp plasma flow control concept at a flow Reynolds number of Rec 􏰇 4:33 􏰉 105.
The alternating current (ac) glow discharge SDBD plasma actuator offers tremendous potential as a flow control device because of its simple lightweight design with no moving parts and low power consumption. It has been shown to provide good control effects at low speeds. In recent years, there have been numerous demonstrations on the use of a SDBD plasma actuator for controlling fluid flows. Examples include exciting boundary-layer instability modes on a sharp cone at Mach 3.5 by Corke et al. [2], boundary-layer control by Roth et al. [3], lift augmentation on a wing section by Corke et al. [4], separation control on a high-angle-of- attack airfoil using plasma actuators by Post and Corke [5], separation control on stationary and oscillating airfoils by Post and Corke [6], plasma flaps and slats for hingeless flight control by Corke et al. [7], boundary-layer flow control by Jacob et al. [8], smart
St U V 􏰳
= = = =
Presented as Paper 0636 at the 45th AIAA Aerospace Sciences Meeting and Exhibit, Reno, NV, 8–11 January 2007; received 28 February 2007; revision received 26 March 2007; accepted for publication 1 April 2007. Copyright © 2007 by authors. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. Copies of this paper may be made for personal or internal use, on condition that the copier pay the $10.00 per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923; include the code 0021-8669/07 $10.00 in correspondence with the CCC.
∗Graduate Research Assistant, Department of Mechanical, Industrial and Manufacturing Engineering. Member AIAA.
†Professor, Department of Mechanical, Industrial and Manufacturing Engineering. Senior Member AIAA.
‡Director, Aerodynamics Group. Senior Member AIAA.
§Aerospace Engineer. Member AIAA.
¶Engineering Specialist.
∗∗Clark Chair Professor, Aerospace and Mechanical Engineering
Department, Associate Fellow AIAA.
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