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Active Cancellation of Tollmien-Schlichting Waves under Varying Inflow Conditions for In-Flight Application

Simon, Bernhard Jochen (2017):
Active Cancellation of Tollmien-Schlichting Waves under Varying Inflow Conditions for In-Flight Application.
Darmstadt, Technische Universität, [Online-Edition: http://tuprints.ulb.tu-darmstadt.de/6161],
[Ph.D. Thesis]

Abstract

Active flow control in laminar boundary layers can reduce wall friction on a wing, if laminar-turbulent transition is delayed. In this thesis, (re-)active flow control for active cancellation of Tollmien-Schlichting (TS) waves in a two-dimensional laminar boundary layer is investigated. The TS-waves that initiate the transition to turbulence are attenuated with a DBD plasma actuator by superposition.

Active wave cancelation requires the use of control algorithms and their stability is influenced by variable inflow conditions. Model-based (Linear-Quadratic-Gaussian) and adaptive control algorithms (filtered-x-LMS) are investigated under realistic (varying) inflow conditions in wind-tunnel and in-flight experiments. The further developed delayed-x-LMS algorithm allows a stable and robust controller operation for active wave cancelation in flight. All experimental results are validated by direct numerical simulations and linear stability theory.

Furthermore, the challenges for the application of DBD plasma actuator arrays to delay natural transition are pointed out. The simplification of transfer paths for reducing the required computational power is discussed.

Item Type: Ph.D. Thesis
Erschienen: 2017
Creators: Simon, Bernhard Jochen
Title: Active Cancellation of Tollmien-Schlichting Waves under Varying Inflow Conditions for In-Flight Application
Language: English
Abstract:

Active flow control in laminar boundary layers can reduce wall friction on a wing, if laminar-turbulent transition is delayed. In this thesis, (re-)active flow control for active cancellation of Tollmien-Schlichting (TS) waves in a two-dimensional laminar boundary layer is investigated. The TS-waves that initiate the transition to turbulence are attenuated with a DBD plasma actuator by superposition.

Active wave cancelation requires the use of control algorithms and their stability is influenced by variable inflow conditions. Model-based (Linear-Quadratic-Gaussian) and adaptive control algorithms (filtered-x-LMS) are investigated under realistic (varying) inflow conditions in wind-tunnel and in-flight experiments. The further developed delayed-x-LMS algorithm allows a stable and robust controller operation for active wave cancelation in flight. All experimental results are validated by direct numerical simulations and linear stability theory.

Furthermore, the challenges for the application of DBD plasma actuator arrays to delay natural transition are pointed out. The simplification of transfer paths for reducing the required computational power is discussed.

Place of Publication: Darmstadt
Divisions: 16 Department of Mechanical Engineering
16 Department of Mechanical Engineering > Fluid Mechanics and Aerodynamics (SLA)
16 Department of Mechanical Engineering > Fluid Mechanics and Aerodynamics (SLA) > Flow control and unsteady aerodynamics
Date Deposited: 16 Jul 2017 19:55
Official URL: http://tuprints.ulb.tu-darmstadt.de/6161
URN: urn:nbn:de:tuda-tuprints-61614
Referees: Tropea, Prof. Dr. Cameron and Grundmann, Prof. Dr. Sven and Henningson, Prof. Dr. Dan
Refereed / Verteidigung / mdl. Prüfung: 27 June 2017
Alternative Abstract:
Alternative abstract Language
Aktive Strömungskontrolle in der laminaren Strömungsgrenzschicht kann die Wandreibung am Tragflügel durch Verzögerung der laminar-turbulenten Transition verringern. In dieser Arbeit wird die (re-)aktive Strömungskontrolle zur Dämpfung von Tollmien-Schlichting (TS) Wellen in einer zweidimensionalen laminaren Grenzschicht untersucht. Die TS-Wellen, welche die Transition einleiten, werden nach dem Superpositionsprinzip mit DBD Plasmaaktuatoren ausgelöscht. Die aktive Wellendämpfung setzt den Einsatz von Regelalgorithmen voraus, deren Stabilität von variablen Anströmbedingungen beeinflusst wird. Der Einsatz modellbasierter (Linear-Quadratic-Gaussian) und adaptiver Regelalgorithmen (filtered-x-LMS) wird in Windkanal- und Flugexperimenten unter realistischen (variablen) Anströmbedingungen untersucht. Die Weiterentwicklung des delayed-x-LMS Algorithmus ermöglicht einen stabilen sowie robusten Betrieb des Reglers für die aktive Wellendämpfung im Flug. Die gewonnenen Ergebnisse werden durch direkte numerische Simulationen sowie lineare Stabilitätstheorie validiert. Die Herausforderungen für den Einsatz von DBD Plasmaaktuator-Arrays zur Verzögerung der natürlichen Transition werden in der Arbeit aufgezeigt. Für die Reduzierung der benötigten Rechenleistung wird die Vereinfachung von Übertragungspfaden diskutiert.German
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