1. Boeing - St.Louis March 7, 2006 Plasma Actuators for Landing Gear Noise Control* F. O. Thomas, A. Kozlov, T.C. Corke * Supported by NASA Langley NAG1-03076 AIAA -2005-3010 Presented at 11th AIAA / CEAS Aeroacoustics Conference, May 25, 2005. Langley Research Center

2. Boeing - St.Louis March 7, 2006 The Plasma Fairing Concept

3. Boeing - St.Louis March 7, 2006 Cylinder Model Utilizing Four Actuators 1.Quartz cylinder wall forms a dielectric barrier: ( thickness of 2.5 mm)‏ 2.Copper foil electrode (6.4 mm)‏ 3.Encapsulated electrode: lead foil (25.4 mm)‏ 1.Inner insulation (7 layers of 0.005” thick Kapton tape)‏ 5.Regions of plasma formation Sinusoidal A.C. voltage is applied at 8.1 kV rms and f = 10 kHz.

4. Boeing - St.Louis March 7, 2006 Cylinder Model Utilizing Four Actuators

5. Boeing - St.Louis March 7, 2006 Single Actuator-Induced Mean Velocity Field Plasma actuator No external flow Plasma-induced Coanda effect

6. Boeing - St.Louis March 7, 2006 Dual Actuator-Induced Mean Velocity No external flow Plasma actuators

7. Boeing - St.Louis March 7, 2006 Steady Actuation : Re D = 30,000

8. Boeing - St.Louis March 7, 2006 Wake Velocity Auto-spectra (Re D = 30,000)

9. Boeing - St.Louis March 7, 2006 Re D =30,000 Unsteady Actuation: 48 Hz (St D =1)‏

10. Boeing - St.Louis March 7, 2006 ReD=30,000 Vorticity Unsteady Actuation: 6Hz

11. Boeing - St.Louis March 7, 2006 Unsteady Symmetric Actuation: Re D = 30,000 48 Hz., 25% Duty Cycle: Vorticity

12. Boeing - St.Louis March 7, 2006 Unsteady Symmetric Actuation: Re D = 30,000 25% Duty Cycle, f =48 Hz (St D =1)‏