Sperotto de Quadros, Régis
Numerical Optimization of Boundary-Layer Control using Dielectric Barrier Discharge Plasma Actuators.
Technische Universität, Darmstadt
[Ph.D. Thesis], (2009)
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|Item Type:||Ph.D. Thesis|
|Title:||Numerical Optimization of Boundary-Layer Control using Dielectric Barrier Discharge Plasma Actuators|
A numerical investigation of active wave cancellation, using a plasma actuator in both continuous and pulsed operation modes, was carried out for a flat-plate boundary layer with an adverse pressure gradient at low Reynolds number. Pulsing was achieved by rectangular and sinusoidal modulation of the high-frequency plasma excitation voltage. A closed-loop control was developed and implemented using Large-Eddy Simulations into a CFD code (FASTEST). With this feed-back control algorithm it was found that the control can be limited to two operating parameters in order to significantly reduce Tollmien-Schlichting waves (TS-waves). The feed-back control algorithm was validated using two existing optimization methods which were also implemented in the code. The first method finds a local minimum of a function with several variables using a pattern search technique that compares function values at the three vertices of a triangle. The second method, known as the trust-region method, is based on quadratic models for derivative-free minimization. It was found that the developed feed-back control works efficiently and can be used to determine the optimum operating parameters of the plasma actuator for cancellation of TS-waves. The amplitude reduction of TS-waves is of interest since it allows for a delay of laminar-to-turbulent transition in the boundary layer, resulting in significant drag reduction.
|Place of Publication:||Darmstadt|
|Classification DDC:||500 Naturwissenschaften und Mathematik > 500 Naturwissenschaften
500 Naturwissenschaften und Mathematik > 510 Mathematik
|Divisions:||16 Department of Mechanical Engineering > Fluid Mechanics and Aerodynamics (SLA)|
|Date Deposited:||28 Jul 2009 08:29|
|Last Modified:||07 Dec 2012 11:55|
|Referees:||Tropea, Dr.Ing Cameron|
|Refereed:||1 July 2009|