Design and evaluation of a flutter-suppression control system for a high-aspect-ratio wing.

Jivan, Shaneel (2017-03)

Thesis (MEng)--Stellenbosch University, 2017.

Thesis

ENGLISH ABSTRACT: Flutter is a form of aeroelastic instability. This instability is prevalent among aircraft which use high-aspect-ratio wings. Previous studies have been conducted in which control surfaces were used to suppress utter using mathematical models to perform the aeroelastic analysis. This thesis documents the design and evaluation of a utter-suppression control system for a highaspect- ratio wing. The project made use of ANSYS software where a numerical Fluid-Structure Interaction (FSI) model was established and used in performing the aeroelastic analysis. The goal of the active controller was to suppress utter by regulating the wing tip displacement with the use of control surfaces. A Linear Quadratic (LQ) controller was constructed and embedded within the FSI model using ANSYS Parametric Design Language (APDL) scripting. Initial simulations indicated that a translational base excitation could not induce aeroelastic instability. However, a rotational base excitation proved to successfully excite utter. Open- and closed-loop simulations were performed at a velocity of 50 m=s. Open-loop simulations indicated that the wing tip displacement was observed to grow without bound. The closed-loop simulations indicated that the LQ controller displayed the capability to suppress utter by increasing the aerodynamic damping of the system. Non-classical utter was encountered at a velocity of 70 m=s.

AFRIKAANSE OPSOMMING: Fladder is 'n vorm van aëroelastiese onstabiliteit. Hierdie onstabiliteit is algemeen onder vliegtuie wat vlerke met 'n hoë slankheidsverhouding gebruik. Vorige studies behels die gebruik van eheeroppervlaktes om fladder met behulp van wiskundige modelle te onderdruk ten einde 'n aëroelastiese analise uit te voer. Hierdie tesis dokumenteer die ontwerp en evaluering van 'n beheerstelsel vir adderonderdrukking. Dié projek het van ANSYS-sagteware gebruik gemaak om 'n numeriese model vir vloei-struktuur-interaksie (Fluid-Structure Interaction [FSI]) daar te stel en te gebruik tydens die aëroelastiese analise. Die doel van die aktiewe beheerder was om adder te onderdruk deur die vlerkpunt-verplasing met behulp van beheeroppervlaktes te reguleer. 'n Line^er-kwadratiese (Linear Quadratic [LQ]) beheerder is saamgestel en ingebed in die FSI-model deur gebruik te maak van ANSYS se Parametriese Ontwerptaal (Parametric Design Language [APDL]). Aanvanklike simulasies het aangedui dat 'n verplasings basisopwekking nie aëroelastiese onstabiliteit kon induseer nie. Daar is egter bewys dat 'n rotasie-basisopwekking wel adder kon opwek. Ope en geslote lus-simulasies is teen 'n snelheid van 50 m=s uitgevoer. Ope lus-simulasies het aangedui dat vlerkpunt-verplasing oneindig toeneem. Geslote lus-simulasies het aangedui dat die line^er-kwadratiese beheerder die kapasiteit vertoon om adder te onderdruk deur die aërodinamiese demping van die sisteem te verhoog. Nie-klassieke adder is teen 'n snelheid van 70 m=s teëgekom.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/101125
This item appears in the following collections: