Plasma Actuator Based Flow Control Using Inherent Flow Instabilities Mo Samimy Gas Dynamics and Turbulence Laboratory Aeronautical and Astronautical Research Laboratories Department of Mechanical and Aerospace Engineering Workshop on AP WIP for ET, FC, and MP Princeton, August 2011
Acknowledgements • Igor Adamovich and Datta Gaitonde • Martin Kearney-Fischer, Ani Sinha, Jin-Hwa Kim, Nathan Webb, Chris Clifford, Jesse Little, Chris Rethmel, Casey Hahn, and Mike Crawley • NASA, AFOSR, AFRL/WPAFB, ONR, and NAVAIR • Dick Miles for organizing the workshop
Flow Control Exploiting Natural Flow Instabilities Using Plasma Actuators • There are many classes of high-speed and high Reynolds number flow of interest to DoD with well known instabilities • Excitation of these instabilities using plasma actuators offers a great opportunity for effective and efficient flow control • A few examples are: – SBLI (in scramjet and in supersonic aircraft inlet) – Mixing/combustion (in tactical aircraft exhaust and in scramjet engine) – Cavity flows (in weapons bay and landing gear) – Flow separation (in fixed wing or rotary aircraft) – Jet noise (in tactical and commercial aircraft)
Flow Control Exploiting Natural Flow Instabilities Using Plasma Actuators • The three selected problems for demonstration are: – Jet noise – Shock/boundary layer interactions (SBLI) – Flow separation over a wing/an airfoil (flow separation) • We have used two classes of plasma actuators to generate perturbations of desired frequency and mode – Localized Arc Filament Plasma Actuators (LAFPAs) for jet noise and SBLI – Nano Second pulse driven Dielectric Barrier Discharge (NS-DBD) actuators for flow separation
Jet Noise and Jet Instabilities • It has been known that: – A jet contains several instabilities and amplifies perturbations over a range of frequencies and modes – The amplified perturbations grow into large-scale structures, dynamics of which are responsible for the peak far-field noise • There are significant clues that dynamics of some structures are less efficient in generating far-field noise • We seek to selectively enhance the less efficient structures using plasma actuators to reduce the far-field noise
Initial Shear Layer and Jet Column Instabilities Forcing Strouhal Number (St DF =fD/U j ) PIV measurements - jet width at half centerline velocity for Mach 0.9 jet (Re D =0.61x10 6 ) forced at m = 0 using 8 LAFPAs
Control Effects on Flow Structures ( M=1.3; Re D =1.07x10 6 ; m= 1 ) St DF =0.33 St DF =0.52 Galilean streamlines superimposed on Q-criterion contours
Control Effects on Flow Structures ( M=1.3; Re D =1.07x10 6 ; m= 1 ) St DF =0.33 St DF =1.05 Galilean streamlines superimposed on Q-criterion contours
Control Effects on Far-Field Noise ( OASPL) – ( M=1.3; m=3 & TTR = 2)
Localized Arc Filament Plasma Actuators (LAFPAs) • A pair of electrodes (1 mm dia. tungsten) connected to a high voltage (~kV) or a low voltage power supply with a transformer constitutes a LAFPA • A LAFPA provides localized high amplitude heating (arc filament cross section is ~1-2 mm 2 ) • We are using 8 actuators with any prescribed frequency, phase, and duty cycle – Frequencies from 0 to 200 kHz – In jet, with 8 actuators could force several azimuthal modes (m=0-3 & ± 1/ ± 2/ ± 4) Actuator Flow • Power requirement is approximately 20-40 W per actuator so it is scalable • LAFPAs provide opportunities for flow control and diagnostics in variety of flows
Shock/Boundary Layer Interaction • Shock wave/boundary layer interactions (SWBLIs) are prevalent in supersonic/hypersonic flows and the cause of unsteady high pressure and thermal loading • While the unsteady nature of the interaction has been recognized for quite sometime , its relatively coherent nature has been recognized more recently, which provides an opportunity for active control Touber and Sandham (2009) 11
Schlieren Image – Mach 2.3 – Variable-Angle Wedge
Surface Pressure PSD in the Interaction Region Mach 2.3; 9 ° Wedge
Streamwise Mean Velocity Profiles in Interaction Region (actuators upstream, but measurement plane within SWBLI region)
Airfoil Lift Characterization Without Flow Control Stall angle ~ 13
With NS-DBD Control ( Re = 1.15x10 6 , α = 18 ° ) • Mach number of 0.26, typical takeoff and landing speed
Concluding Remarks • Over the past 10 years or so, there has been tremendous progress on the development and use of plasma actuators for flow control • This is a multi-disciplinary field requiring larger efforts bringing together experimental and computational fluid dynamics and plasma dynamics communities • The field also requires larger focused efforts to scale up the technology
References • Samimy, M., Kim, J.-H., Kastner, J., Adamovich, I., and Utkin, Y., “Active Control of High Speed and High Reynolds Number Jets Using Plasma Actuators,” Journal of Fluid Mechanics, Vol. 578, pp. 305-330, May 2007. • Utkin, Y., Keshav, S., Kim, J.-H., Kastner, J., Adamovich, I., and Samimy, M., “Use of Localized Arc Filament Plasma Actuators for High Speed Jet Control,” Journal of Physics D: Applied Physics, Vol. 40, pp. 685-694, February 2007. • Samimy, M., Kim, J.-H., Kearney-Fischer, M., and Sinha, A., “Acoustic and Flow Fields of an Excited High Reynolds Number Axisymmetric Perfectly-Expanded Supersonic Jet,” Journal of Fluid Mechanics, Vol. 656, August 2010, pp. 507-529. • Kearney-Fischer, M., Kim, J.-H., and Samimy, M., “A Study of Mach Wave Radiation Using Active Control,” Journal of Fluid Mechanics, Vol. 681, August 2011, pp. 261-292. • Kim, J.-H, Kearney-Fischer, M., Samimy, M., and Gogineni, S., “Far -field Noise Control in Supersonic Jets Using Conical and Contoured Nozzles,” ASME Journal of Engineering for Gas Turbine and Power, Vol. 133, August 2011, pp 081201-1 to 081201-9. • Webb, N., Clifford, C., and Samimy, M., “Preliminary Results on Control of Shock Wave/Boundary Layer Interaction Using Plasma Actuators,” 41 st AIAA Fluid Dynamics Conference in Hawaii, AIAA-2011-3426. • Rethmel, C., Little, J., Takashima, K., Nishihara, M., Adamovich, I., and Samimy, M., “Flow Separation Control over and Airfoil with Nanosecond Pulse Driven DBD Plasma Actuators,” AIAA Paper No. 2011-487, January 2011. • Takashima K, Zuzeek Y, Lempert WR, Adamovich IV (2010) Characterization of Surface Dielectric Barrier Discharge Plasma Sustained by Repetitive Nanosecond Pulses. AIAA Paper 2010-4764
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