Author

Lamiae Taoudi

Advisor

Sescu, Adrian

Committee Member

Thompson, David S.

Committee Member

Janus, J. Mark

Date of Degree

1-1-2016

Document Type

Graduate Thesis - Open Access

Major

Aerospace Engineering

Degree Name

Master of Science

Department

Department of Aerospace Engineering

Abstract

Görtler vortices evolve in boundary layers over concave surfaces as a result of the imbalance between centrifugal forces and radial pressure gradients. Depending on various geometrical and free-stream flow conditions, these instabilities may lead to secondary instabilities and early transition to turbulence. In this thesis, a control algorithm based on the boundary region equations is applied to reduce the strength of the Görtler instabilities by controlling the energy of the fully developed vortices, using either local wall deformations or blowing/suction at the wall. A proportional-integral control scheme is utilized to deform the wall or to provide transpiration velocity, where the inputs are either the wall-normal or streamwise velocity components in a plane that is parallel to the wall. The results show that the control based on wall deformation using wall-normal velocity components is more effective in tempering the vortex during its streamwise growth by almost one or two orders of magnitude.

URI

https://hdl.handle.net/11668/19990

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