Search for dissertations about: "DDES"

Found 5 swedish dissertations containing the word DDES.

  1. 1. Integrated Duct Aerodynamics

    Author : Elias Siggeirsson; Chalmers University of Technology; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; DDES; RANS; CFD; Compressor duct; Spalart-Allmaras;

    Abstract : Air traffic is rapidly increasing, with no sign of slowing down, resulting in increased green-house gases emission. With emission criteria becoming stricter every year, the aircraft design is subjected to continuous improvements. The development of more efficient aircraft engines plays a central role in the strive towards lower emission levels. READ MORE

  2. 2. Turbulence-resolving Simulations of Swirling Flows

    Author : Ardalan Javadi; Chalmers University of Technology; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Swirling Flow; URANS; Hydropower; Hybrid URANS-LES; SAS; Flow Control; Turbulence Modeling; Vortex Breakdown; DDES; LES;

    Abstract : A series of numerical investigations is undertaken using a wide range of turbulence mod-els including conventional and non-conventional URANS models, hybrid URANS-LESmethods and LES to capture a large variety of physical mechanisms that produce pres-sure pulsations in the swirling flows. The available knowledge about these pulsations,which are usual in hydropower, are still far from complete. READ MORE

  3. 3. Aerodynamics of an Aeroengine Intermediate Compressor Duct: Effects from an Integrated Bleed System

    Author : Elias Siggeirsson; Chalmers University of Technology; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Turbomachinery; CFD; SBES; Hybrid RANS LES; DDES; rotor off-take; S-shaped duct; Intermediate Compressor Duct; Bleed system; Dual-time-stepping;

    Abstract : With the successful development of high-bypass-ratio turbofan engines, major aerodynamic components have been optimized and continuous efficiency improvements are getting harder to maintain. Therefore, to meet the requirements of lower emission of greenhouse gases, auxiliary modules such as intermediate ducts are receiving increasing interest. READ MORE

  4. 4. Slipstream and Flow Structures in the Near Wake of High-Speed Trains

    Author : Tomas W. Muld; Gunilla Efraimsson; Dan S. Henningson; Chris Baker; KTH; []
    Keywords : ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Abstract : Train transportation is a vital part of the transportation system of today. Asthe speed of the trains increase, the aerodynamic effects become more impor-tant. One aerodynamic effect that is of vital importance for passengers’ andtrack workers’ safety is slipstream, i.e. READ MORE

  5. 5. Analysis of the Unsteady Flow Field of a Passenger Vehicle

    Author : Lennert Sterken; Chalmers University of Technology; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Wind tunnel; Wake; CFD; Pressure measurements; Extensions; Yaw response; External aerodynamics; Aerodynamic forces;

    Abstract : Political legislation and consumer requirements for a sustainable society require that vehicle manufacturers focus on reduced fuel consumption and lower emissions. Areduction in the overall energy consumption can be directly linked to a decrease of the driving resistance, where the aerodynamic drag significantly contributes at velocities above 70km/h. READ MORE