Application of Koopman Mode Decomposition Methods in Dynamic Stall
Abstract
Dynamic stall is an inherently unsteady phenomenon which is significantly affected by the interaction of the laminar/turbulent boundary layer transition, flow separation, vortex growth and propagation, and reattachment of the flow. During dynamic stall, large peaks in lift, pitching moment and drag appear, and these cause an undesirable increase in the mean drag. Dynamic stall can also lead to potentially fatal structural loads due to strong vibrations of flexible aerodynamic surfaces. Despite extensive analytical, numerical, and experimental efforts to study dynamic stall motivated by the interest in improving maneuverability and performance of rotorcraft air vehicles, progress is needed for the full understanding and prediction of the relevant complex fluid dynamic mechanisms. Dominant mode extraction methods provide simplification of the unsteady flow phenomena by separating them into individual modes. Proper Orthogonal Decomposition of the velocity field is a popular technique to achieve this goal. However it can only reveal the energetically dominant coherent flow patterns, and has been shown to fail to capture subtle, oscillatory phenomena that are known to be important in dynamic stall physical processes such as the shear layer separation. We propose higher resolution models of dynamic stall.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 11, 2014
- Accession Number
- ADA606543
Entities
People
- Igor Mezić
- Maria Fonoberova
- Sophie Loire