In this research the γ-Rẽ<sub>θt</sub> transition model is combined with the k-ω SST turbulence model to predict the transition region for a laminar-turbulent boundary layer and redesign the geometry to achieve lower skin friction drag coefficients. The present work addresses several modifications necessary for a robust transition model and investigates the accuracy of the model for a wide range of angles of attack and Reynolds numbers. The transition model is employed to predict the transition locations and an assessment of the various transition mechanisms, Reynolds number effects, sectional characteristics, and aerodynamic performance for two subsonic airfoils are presented with comparisons to experimental data and numerical solutions. Discrete adjoint equations for the transition and turbulence models are derived and implemented into the design framework. The adjoint-based optimization procedure is employed to optimize the S809 wind turbine profile and NLF(1)-0416 airfoil to postpone the onset of transition and extend the natural laminar region of the transitional flow for minimizing the total drag, while maintaining the lift, or maximizing the lift-to-drag ratio. The obtained results demonstrate the ability of the developed optimization framework to design new natural laminar flow airfoils. / Dans cette recherche, le modele de transition γ-Rẽ<sub>θt</sub> est combine avec le modele de turbulence k-ω SST afin de predire la transition vers le regime turbulent et d'obtenir des formes aerodynamiques au frottement visqueux minimal. Nous presentons les modifications necessaires a l'amelioration de la robustesse du modele de transition et etudions la precision du modele pour une large gamme d'angles d'attaque et de nombres de Reynolds. Le modele de transition est utilise pour predire le point de transition, pour evaluer les mecanismes de transition ainsi que les differents effets relies au nombre de Reynolds, et pour etudier les caracteristiques et les performances aerodynamique de deux profils aerodynamiques. Des comparaisons avec des donnees experimentales et des solutions numeriques sont presentees. Les equations adjointes discretes des modeles de transition et de turbulence sont derivees et employees dans un processus d'optimization. Cette procedure d'optimisation est utilisee pour modifier le profil d'eolienne S809 et le profil NLF(1)-0416 afin de retarder la transition et d'etendre la zone laminaire de l'ecoulement, de minimiser le coefficient de trainee totale tout en maintenant la portance, ou de maximiser la finesse aerodynamique. Les resultats obtenus demontrent la capacite du processus d'optimisation developpe} a concevoir de nouveaux profils ecoulement laminaire naturel.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.119529 |
| Date | January 2013 |
| Creators | Khayatzadeh, Peyman |
| Contributors | Sivakumaran Nadarajah (Supervisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Mechanical Engineering) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | Electronically-submitted theses. |
Page generated in 0.0248 seconds