# Order of Magnitude Improvement of SDBD Actuator Effect

## Presentation on theme: "Order of Magnitude Improvement of SDBD Actuator Effect"— Presentation transcript:

Order of Magnitude Improvement of SDBD Actuator Effect
T. Corke, F. Thomas, D. Orlov, M. Iqbal, A. Kozlov, H. Othman, D. Shatzman Center for Flow Physics and Control Aerospace and Mechanical Engineering University of Notre Dame Nov. 8, 2006 AF Academy Workshop on Plasma Actuators

Questions: How do we improve the performance of SDBD plasma actuators?
What are the governing properties? What is the ultimate performance limit? Nov. 8, 2006 AF Academy Workshop on Plasma Actuators

Approach: Develop space-time model for ionization in SDBD operation.
Include amplitude and frequency effects. Not including maximum limits. Compare to experiments. Perform experiments that investigate limiting conditions on SDBD design and operation parameters. Develop a theory to be included in space-time model. Nov. 8, 2006 AF Academy Workshop on Plasma Actuators

SDBD Actuators: What we know
Three time scales: Micro discharges (nsec) a.c. period (.1ms) Fluid response (10ms) Ionization space-time dependent. Static models give wrong results (e.g. fb~V2). Temporal/space-uniform models give correct V-dependence (fb~V7/2), need spatial weighting Space-time models give correct V, frequency and space dependence (Orlov, 2006). Nov. 8, 2006 AF Academy Workshop on Plasma Actuators

Steps to model actuator in flow
Space-time electric potential,  Space-time body force Flow solver with body force added Nov. 8, 2006 AF Academy Workshop on Plasma Actuators

Space-time model Physical space over the encapsulated electrode is divided into N parallel networks. Each parallel network consists of air capacitor, dielectric capacitor, plasma resistive elements and zenor diodes. Nov. 8, 2006 AF Academy Workshop on Plasma Actuators

Model circuit elements
air capacitor dielectric capacitor Voltage on the dielectric surface in the n-th sub-circuit Plasma current Nov. 8, 2006 AF Academy Workshop on Plasma Actuators

Model Time Series Vn (t) Ipn (t) t/Ta.c. t/Ta.c. 5 1 5 1 Nov. 8, 2006
AF Academy Workshop on Plasma Actuators

Model Space-time Characteristics
Experiment Illumination Model Ip(t) dxp/dt (xp)max Nov. 8, 2006 AF Academy Workshop on Plasma Actuators

Plasma Propagation Characteristics
Effect of Vapp dxp/dt vs Vapp (xp)max vs Vapp Nov. 8, 2006 AF Academy Workshop on Plasma Actuators

Plasma Propagation Characteristics
Effect of fa.c. dxp/dt vs fa.c. (xp)max vs fa.c. Nov. 8, 2006 AF Academy Workshop on Plasma Actuators

Numerical solution for (x,y,t)
Model provides time-dependent B.C. for  Nov. 8, 2006 AF Academy Workshop on Plasma Actuators

Body Force, fb(x,t) Y Normalized fb(x,t) t/Ta.c.=0.2 t/Ta.c.=0.7
Nov. 8, 2006 AF Academy Workshop on Plasma Actuators

Frequency Dependence of fb & Wp
Impact: Optimum frequency for body force. Depends on actuator capacitance. Nov. 8, 2006 AF Academy Workshop on Plasma Actuators

What limits maximum body force?
SDBD Plasma actuator is voltage driven, fb~V7/2. Not current driven like voice-coil type actuators. For fixed power (I·V), one needs to limit current to maximize voltage. What governs maximum achievable voltage for fixed power? Nov. 8, 2006 AF Academy Workshop on Plasma Actuators

Maximum Voltage Optimization
Investigated different parameters on thrust produced by actuator Nov. 8, 2006 AF Academy Workshop on Plasma Actuators

Order of Magnitude Improvement
Imax Imax Material  Quartz 3.8 Kapton 3.4 Teflon 2.0 Imax Imax Nov. 8, 2006 AF Academy Workshop on Plasma Actuators

Premise The maximum voltage at fixed power is limited by local electric field exceeding breakdown of air. Thicker dielectrics and/or lower dielectric constants reduce capacitance of actuator and reduce concentration of electric field lines. Other parameters? Nov. 8, 2006 AF Academy Workshop on Plasma Actuators

Effect of frequency on Vmax
1kHz 0.25in. quartz glass 2kHz Vmax(f) 4kHz 8kHz Nov. 8, 2006 AF Academy Workshop on Plasma Actuators

Effect of dielectric thickness on Vmax
quartz glass; 1,2,4,8kHz Tmax ~ Vmax fa.c. ~ (t/)d Nov. 8, 2006 AF Academy Workshop on Plasma Actuators

Tmax Efficiency 0.25in. quartz glass Nov. 8, 2006 AF Academy Workshop
on Plasma Actuators

Answers to Questions: To improve the performance of SDBD plasma actuators? Maximize V for fixed power. Minimize I by preventing formation of strong plasma filaments. Governing properties? Dielectric design (t & ) and a.c. frequency. Ultimate performance limit? Maximum local E-field for air breakdown? Nov. 8, 2006 AF Academy Workshop on Plasma Actuators