Sökning: "Dan Henningson"

Visar resultat 11 - 15 av 51 avhandlingar innehållade orden Dan Henningson.

1. 11. Flow control and reduced-order modelling of transition in shear flows

   Författare :Reza Dadfar; Dan Henningson; Vasssilis Theofilis; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Flow control; plasma actuator; wing; leading edge; flat plate; wind turbine; optimal controller; model reduction; proper orthogonal decomposition; dynamic mode decomposition.;

   Sammanfattning : In this thesis direct numerical simulation is used to investigate the possibility to delay the transition from a laminar to a turbulent flow in boundary layer flows. Furthermore, modal analysis techniques are used to identify the coherent structures in wind turbine wake. LÄS MER

3. 12. Numerical studies of receptivity, stability and transition of wing and turbine blade boundary layers

   Författare :Luca De Vincentiis; Ardeshir Hanifi; Dan S. Henningson; Stefania Cherubini; KTH; []
   Nyckelord :Teknisk mekanik; Engineering Mechanics;

   Sammanfattning : In the present thesis, receptivity, stability and laminar-turbulent transition of different boundary-layer flows are addressed and investigated by means of direct numerical simulations. In particular, flows over a wing and a low-pressure-turbine (LPT) blade have been the main focus. LÄS MER

4. 13. Direct Numerical Simulation of Boundary-layer Transition with Free-stream Turbulence

   Författare :Kristina Durovic; Dan Henningson; Ardeshir Hanifi; Philipp Schlatter; Tamer Zaki; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Engineering Mechanics; Teknisk mekanik;

   Sammanfattning : This thesis considers the generation and influence of free-stream turbulence toboundary layer transition on both flat and curved bodies in the flow. Variousflow configurations such as flow around the flat plate with a sharp leading edgeand low-pressure turbine blades are considered. LÄS MER

5. 14. Numerical Computations of Wakes Behind Wind Farms

   Författare :Ola Eriksson; Stefan Ivanell; Simon-Philippe Breton; Anna Rutgersson; Dan Henningson; Niels Troldborg; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Wind turbine; Wind power; Wind farm; Wakes; Long distance wakes; Farm-Farm; Farm to farm interaction; Wind farm cluster; Large Eddy simulations; LES; Actuator disc method; ACD; CFD; Ellipsys3D;

   Sammanfattning : More and larger wind farms are planned offshore. As the most suitable build sites are limited wind farms will be constructed near to each other in so called wind farm clusters. Behind the wind turbines in these farms there is a disrupted flow of air called a wake that is characterized by reduced wind speed and increased turbulence. LÄS MER

7. 15. Adaptive and model-based control in laminar boundary-layer flows

   Författare :Nicolò Fabbiane; Dan S. Henningson; Aimee S. Morgans; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Flow control; Control theory; Optimal control; Adaptive control; Boundary-layer flow; Fluid dynamics; Plasma actuator; Surface hot-wire; Transition delay;

   Sammanfattning : In boundary-layer flows it is possible to reduce the friction drag by breaking the path from laminar to turbulent state. In low turbulence environments, the laminar-to-turbulent transition is dominated by local flow instabilities – Tollmien-Schlichting (TS) waves – that exponentially grows while being con- vected by the flow and, eventually, lead to transition. LÄS MER