Sökning: "Modal Decomposition"

Visar resultat 1 - 5 av 30 avhandlingar innehållade orden Modal Decomposition.

  1. 1. Modal Decomposition of Separated Nozzle Flow

    Författare :Ragnar Larusson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Arnoldi; axisymmetric convergent-divergent nozzle; Mode Decomposision; Flow Separation; Resonance.; Dynamic Mode Decomposision; Computational Fluid Dynamics;

    Sammanfattning : The applicability of two different eigenvalue algorithms coupled with an axisymmetric RANS solver to predict the eigenmodes of separated supersonic flow inside an axisymmetric convergent-divergent nozzle was investigated. These are the Arnoldi and the Dynamic Mode Decomposition (DMD) algorithms, respectively. LÄS MER

  3. 2. Modal Analysis of Supersonic Flow Separation in Nozzles

    Författare :Ragnar Larusson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Separated Nozzle Flow; Dynamic Mode Decomposition; Hybrid RANSLES; CFD; Modal Analysis; Arnoldi;

    Sammanfattning : Operating a convergent-divergent nozzle under overexpanded conditions can lead to supersonic flow separation in the divergent section of the nozzle. In this case, an attached oblique shock wave forms at the separation base. LÄS MER

  4. 3. Drag Reduction by means of Active Flow Control Applied on a Generic Truck A-pillar: a Numerical and Experimental Study

    Författare :Guglielmo Minelli; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; PANS; Large Eddy Simulation; Wind Tunnel.; Bluff Body Flow; Modal Decomposition; Experiments; Vehicle Aerodynamic; POD; Active Flow Control; LES; Partially Averaged Navier Stokes; AFC;

    Sammanfattning : The overall goal of this thesis is to isolate and control the flow mechanism characterizing the flow separation occurring at the A-pillar of a truck. The study aims to gain knowledge of the flow physics of the separation mechanism, and to eventually suppress the afore mentioned separation by means of an Active Flow Control. LÄS MER

  5. 4. Predicting Xenon Oscillations in PWRs using Intrusive Reduced Order Modelling

    Författare :Kristoffer Pedersen; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Reduced Order Modeling; Modal Decomposition; Multi-Group Diffusion Theory; Xenon Oscillations;

    Sammanfattning : The increasing presence of intermittent energy sources in the Swedish electricity grid necessitates a transition of Swedish nuclear reactors from constant base load operation to load-following mode. However, such changes in power can induce xenon oscillations, a phenomenon that poses operational challenges and the risk of fuel damage. LÄS MER

  7. 5. 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