Avancerad sökning

Hittade 3 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. Turbulent Boundary Layer Separation and Control

    Författare :Ola Lögdberg; P. Henrik Alfredsson; Jens Fransson; Guido Buresti; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Flow control; adverse pressure gradient APG ; flow separation; vortex generators; jet vortex generators; pulsed jet vortex generators; Fluid mechanics; Strömningsmekanik;

    Sammanfattning : Boundary layer separation is an unwanted phenomenon in most technical applications, as for instance on airplane wings, ground vehicles and in internal flow systems. If separation occurs, it causes loss of lift, higher drag and energy losses. It is thus essential to develop methods to eliminate or delay separation. LÄS MER

  3. 2. Numerical Modelling of Fuel Sprays

    Författare :Christer Bergström; Strömningsteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; vibration and acoustic engineering; vacuum technology; hydraulics; Mechanical engineering; Gas turbine.; Temperature fluctuations. Diesel engine; Counter rotating Vortex Pair; CVP; Large Eddy Simulation; Droplet Evaporation; Turbulent flows; LES; Spray; Modelling; Break-up; Maskinteknik; hydraulik; vakuumteknik; vibrationer; akustik; Carbochemistry; petrochemistry; fuels and explosives technology; Petrokemi; bränslen; sprängämnen;

    Sammanfattning : The way the fuel is introduced into the combustion chamber is one of the most important parameters for the power output and the generation of emissions in the combustion of liquid fuels. The interaction beween the turbulent gas flow field and the liquid fuel droplets, the vaporisation of them and the mixing of the gaseous fuel with the ambient air that are vital parameters in the combustion process. LÄS MER

  4. 3. Boundary layer streaks as a novel laminar flow control method

    Författare :Sohrab Sattarzadeh Shirvan; Jens H. M. Fransson; Edward B. White; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; boundary layer stability; laminar to turbulent transition; laminar flow control; drag reduction; Tollmien-Schlichting waves; oblique waves; streaky boundary layers; miniature vortex generators; discrete suction;

    Sammanfattning : A novel laminar flow control based on generation of spanwise mean velocity gradients (SVG) in a flat plate boundary layer is investigated where disturbances of different types are introduced in the wall-bounded shear layer. The experimental investigations are aimed at; (i) generating stable and steady streamwise streaks in the boundary layer which set up spanwise gradients in the mean flow, and (ii) attenuating disturbance energy growth in the streaky boundary layers and hence delaying the onset of turbulence transition. LÄS MER