Sökning: "high turbulence levels"

Visar resultat 1 - 5 av 54 avhandlingar innehållade orden high turbulence levels.

  1. 1. Direct numerical simulation of turbulent premixed flames at high Karlovitz numbers: structure and modelling

    Författare :Thommie Nilsson; Strömningsteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Direct numerical simulation; Computational fluid dynamics; Combustion model; Premixed flame; Turbulence; Karlovitz number;

    Sammanfattning : There has been recent increased interest in premixed flames and in particular for use in gas turbines for power generation. This is a development that follows from increasing demands for high efficiency and low emissions of NOx, which can be achieved by using premixed flames and lean pre-heated mixtures, often close to the lean flammability limit. LÄS MER

  3. 2. Development and analysis of turbulence models for flows with strong curvature and rotation

    Författare :Olof Grundestam; KTH; []
    Nyckelord :Turbulence model; nonlinear modelling; streamline curvature; high-lift aerodynamics;

    Sammanfattning : An explicit algebraic Reynolds stress model (EARSM) based ona pressure strain rate model including terms tensoriallynonlinear in the mean velocity gradients is developed in orderto improve predictions for .ows with strong curvature and/orrotation. LÄS MER

  4. 3. On Turbulent Wall Jets

    Författare :Hans Abrahamsson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; self-preservation; similarity theory; scaling laws; local flow reversals; high turbulence levels; turbulent kinetic energy budget; two-dimensional; turbulent; hot-wire anemometry; wall jet; three-dimensional; pulsed hot-wire anemometry;

    Sammanfattning : An experimental investigation of the two- and three-dimensional turbulent wall jets has been conducted. The measurements have been performed using different hot-wire techniques in large scale wall jet facilities, and the measurements were focused on the fully-developed region of the flow. LÄS MER

  5. 4. Diluted Operation of a Heavy-Duty Natural Gas Engine - Aiming at Improved Effciency, Emission and Maximum Load

    Författare :Mehrzad Kaiadi; Förbränningsmotorer; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Turbulence; Natural gas engine; Dilution limit; VGT; Cyclic variation; Closed-loop control; Heavy-duty;

    Sammanfattning : Most heavy-duty engines are diesel operated. Severe emission regulations, high fuel prices, high technology costs (e.g. catalysts, fuel injection systems) and unsustainably in supplying fuel are enough reasons to convenience engine developers to explore alternative technologies or fuels. LÄS MER

  7. 5. Exploring the nature of ISM turbulencein disc galaxies

    Författare :Timmy Ejdetjärn; Göran Östlin; Oscar Agertz; Garrelt Mellema; Troels Haugbølle; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; galaxies; galaxy; disc galaxy; star formation; ISM; interstellar medium; kinematics; dynamics; evolution; turbulence; numerical; Astronomy; astronomi; teoretisk astrofysik; Theoretical Astrophysics;

    Sammanfattning : Galaxy formation is a continuous process that started only a few hundred million yearsafter the Big Bang. The first galaxies were very volatile, with bursts of star formationand disorganised gas motions. LÄS MER