Sökning: "vortex drag"

Visar resultat 1 - 5 av 30 avhandlingar innehållade orden vortex drag.

1. 1. Wind turbine wakes : controland vortex shedding

   Författare :Davide Medici; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Wind Energy; Power Optimisation; Active Control; Yaw; Vortex; Mechanical energy engineering; Mekanisk energiteknik;

   Sammanfattning : Wind tunnel studies of the wake behind a model wind turbine have been made in order to get a better understanding of wake development as well as the possibility to predict the power output from downstream turbines working in the wake of an upstream one. Both two-component hot-wire anemometry as well as particle image velocimetry (PIV) have been used to map the flow field. LÄS MER

3. 2. Computational hydrodynamics applied to an America's Cup class keel - best practice and validation of methods

   Författare :Sofia Werner; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; CFD; America s Cup; induced drag; wind tunnel; winglet; validation; keel; vortex drag; wake survey;

   Sammanfattning : Numerical predictions of the flow around yacht keels can be performed with various types of methods. In this work computational fluid dynamic (CFD) computations are validated against wind tunnel studies of an America's Cup Class keel with the purpose of investigating the accuracy that can be achieved with CFD, which methods that are suitable and how they should be used in the best way. LÄS MER

4. 3. Potential Flow Panel Methods for the Calculation of Free-surface Flows with Lift

   Författare :Carl-Erik Janson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; desingularized; shape optimization; Rankine source; waves; OCTOPUS; dipole; MMA; Dawson operator; boundary layer; vortex; Method of Moving Asymptotes; nonlinear; sailing yacht; four point operator; surface piercing wing; Navier-Stokes; numerical method; lift force; raised panel method; discrete Fourier transform; collocation point shift; potential flow; CFD; free surface; induced drag; SHIPFLOW; dispersion; damping; analytical method; hydrofoil;

   Sammanfattning : Two non-linear Rankine-source panel methods are developed and implemented in the same computer code. The first method uses a four-point upwind operator on the free-surface to compute the velocity derivatives and to enforce the radiation condition while the second method uses an analytical expression for the velocity derivatives and a collocation point shift one panel upstream to prevent upstream waves. LÄS MER

5. 4. Minimize Vortex Drag of a Passenger Car

   Författare :Ture Jesper Marklund; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Boundary layer; Bluff bodies; Vehicle aerodynamics; Wake flow; CFD;

   Sammanfattning : The aerodynamic drag force is the single biggest resistance force for a passenger car toovercome at highway speeds. Since all driving resistance forces can be directly linked tofuel consumption this has become a significant priority in recent years. LÄS MER

7. 5. Vortex generators and turbulent boundary layer separation control

   Författare :Ola Lögdberg; Henrik Alfredsson; Per-Åge Krogstad; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; turbulent boundary layer separation; adverse pressure gradient; vortex generators; control of separation; Fluid mechanics; Strömningsmekanik;

   Sammanfattning : Boundary layer separation is usually an unwanted phenomenon in most technical applications as for instance on airplane wings, on ground vehicles and in internal flows such as diffusers. If separation occurs it leads to loss of lift, higher drag and results in energy losses. LÄS MER