Sökning: "Flame instabilities"

Visar resultat 1 - 5 av 12 avhandlingar innehållade orden Flame instabilities.

  1. 1. Experimental and Numerical Investigations of Flames Stabilized by Swirl Flow and Bluff-body:Flame Structures and Flame Instabilities

    Författare :Yiheng Tong; Kraftverksteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Flame structures; Flame instabilities; Blowout limits; Flashback; Swirl Flow; Bluff-body; Chemiluminescence; PIV;

    Sammanfattning : Combustion and its control are essential to our existence on this planet since we knew it. Nowadays, the largest share of the world’s electricity and most of our transportation systems are powered by combustion. In addition, industrial processes also rely heavily upon combustion. LÄS MER

  2. 2. Numerical study of flame dynamics

    Författare :Arkady Petchenko; Vitaly Bychkov; Leonid Kagan; Umeå universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; combustion; Direct Numerical Simulation DNS ; turbulence; flame-vortex interaction; flame acceleration; flame-acoustic interaction; Physics; Fysik;

    Sammanfattning : Modern industrial society is based on combustion with ever increasing standards on the efficiency of burning. One of the main combustion characteristics is the burning rate, which is influenced by intrinsic flame instabilities, external turbulence and flame interaction with walls of combustor and sound waves. LÄS MER

  3. 3. Theoretical and Experimental Investigations of Nonlinear Flame Instability

    Författare :Li-Zheng Ma; Chalmers University of Technology; []
    Nyckelord :nonlinear hydrodynamic instability; flame propagation and stretch effects; shock induced flame instability; tulip flame formation; interface tracking; the Schlieren technique; level set approach;

    Sammanfattning : Flame instability is both important and difficult to understand. Mechanisms of instability are complex, because instability often involves an interaction between several different physical phenomena, such as an unsteady chemical reaction, unsteady flame propagation generating an unsteady flow, acoustic waves or shock waves. LÄS MER

  4. 4. Interaction of sound waves with a swirl stabilized wood powder flame and their effects on flame characteristics

    Författare :Burak Göktepe; Luleå tekniska universitet; []
    Nyckelord :ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Energy Engineering; Energiteknik;

    Sammanfattning : Swirling flows have been widely used for many years in engineering applications such as; chemical and mechanical mixing devices, separation units, spray drying technologies, turbo machinery and combustion systems. In practical combustion applications, swirl motion has been adopted to the incoming reactant flows in order to enhance the mixing of fuel and oxidizer and to improve flame stabilization and establishment, especially in regions of relatively low velocities, by recirculating hot product gas to the incoming reactants. LÄS MER

  5. 5. Frequency Domain Linearized Navier-Stokes Equations Methodology for Aero-Acoustic and Thermoacoustic Simulations

    Författare :Wei Na; Gunilla Efraimsson; Susann Boij; Martinez Lera Paula; KTH; []
    Nyckelord :ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; Linearized Navier-Stokes Equations; frequency domain; fluid equivalent model; hybrid liner; thermoacoustic instabilities; Rijke-tube; Teknisk mekanik; Engineering Mechanics;

    Sammanfattning : The first part of the thesis focuses on developing a numerical methodology to simulate the acoustic properties of a hybrid liner consisting of a perforated plate, a porous layer and a Helmholtz cavity. Liners are always a standard way to reduce noise in today’s aeroengines, e.g. LÄS MER