Sökning: "induced drag"

Visar resultat 1 - 5 av 40 avhandlingar innehållade orden induced drag.

1. 1. 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

3. 2. Effect of drag reducing plasma actuators using LES

   Författare :Romain Futrzynski; Gunilla Efraimsson; P. Henrik Alfredsson; Emma Alenius; Johan Revstedt; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; flow control; drag reduction; plasma actuator; DMD; LES; optimization; pulsating flow; strömningskontroll; motståndsminskning; plasmaaktuator; DMD; LES; optimering; pulserande strömning; Engineering Mechanics; Teknisk mekanik;

   Sammanfattning : The work performed in this thesis explores new ways of reducing the drag of ground vehicles. Specifically, the effect of plasma actuators are investigated numerically with the intention to delay separation around a half-cylinder, a geometry chosen to represent a simplified A-pillar of a truck. LÄS MER

4. 3. Active Flow Control for Drag Reduction of Heavy Vehicles

   Författare :Mohammad El-Alti; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Active and Passive Flow Control; Tilt-rotor wing; Large-eddySimulation; Heavy vehicles; optimization; Full-scale road test; Trucks; Bluff-body; Wake; Drag reduction; Aircrafts; Response surface methodology; Synthetic-jet Actuator;

   Sammanfattning : This thesis considers the aerodynamics of trucks. The work focuses on the aerodynamic drag caused by the wake. Bluff-body flows are dominated by large dissipative vortex-shedding wakes with a low mean pressure compared to the high pressure on their frontal area. LÄS MER

5. 4. 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

7. 5. Vane applications and vane induced flow

   Författare :Fredrick Marelius; KTH; []
   Nyckelord :vane; erosion; shore protection; vortex; scour; ;

   Sammanfattning : Vanes are essentially small aspect ratio foils used forguiding sediment, by means of affecting the flow features. Theyare usually placed on the river bed and aligned with an angleof attack to the approach flow, thereby inducing a secondaryflow component that is used for guiding sediment in a desireddirection. LÄS MER