Sökning: "Boundary-layer receptivity"

Visar resultat 6 - 10 av 16 avhandlingar innehållade orden Boundary-layer receptivity.

  1. 6. Oblique waves in boundary layer transition

    Författare :Stellan Berlin; KTH; []
    Nyckelord :;

    Sammanfattning : Traditional research on laminar-turbulent transition has focused on scenarios that are caused by the exponential growth of eigensolutions to the linearized disturbance equations, e.g. two-dimensional Tollmien-Schlichting waves. LÄS MER

  3. 7. On stability, transition and turbulence in three-dimensional boundary-layer flows

    Författare :Seyed Mohammd Hosseini; Ardeshir Hanifi; Spencer Sherwin; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Receptivity; stability; optimal growth; three-dimensional bound- ary layers; crossflow instability; roughness control; freestream turbulence; sec- ondary instability; transition; turbulence;

    Sammanfattning : A lot has changed since that day on December 17, 1903 when the Wright brothers made the first powered manned flight. Even though the concepts behind flying are unaltered, appearance of stat-of-the-art modern aircrafts has undergone a massive evolution. LÄS MER

  4. 8. An experimental investigation of disturbance growth in boundary layer flows

    Författare :Thomas Kurian; P. Henrik Alfredsson; Jens H. M. Fransson; Edward B. White; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Fluid mechanics; Strömningsmekanik; Other engineering mechanics; Övrig teknisk mekanik;

    Sammanfattning : This thesis deals with the early stages of transition to turbulence in two different baseflows, namely the Falkner-Skan-Cooke boundary layer (FSC) and the asymptotic suction boundary layer (ASBL). Grid-generated turbulence is studied in order to characterise the isotropy levels, free-stream turbulence levels and characteristic length scales that will be present in the receptivity study. LÄS MER

  5. 9. Laninar-turbulent boundary layer transition influenced by free stream turbulence

    Författare :Jonas Westin; KTH; []
    Nyckelord :;

    Sammanfattning : Laminar-turbulent transition in a flat plate boundary layerhas been considered, with a special emphasis on the influencefrom free stream turbulence (FST)First, experiments on linear stability ofTollmien-Schlichting (TS) waves in a Blasius boundary layer wasstudied. This is a well-known example from hydrodynamicstability theory, which has hitherto suffered from unresolveddiscrepancies between experiments and linear theory. LÄS MER

  7. 10. Receptivity of crossflow-dominated boundary layers

    Författare :David Tempelmann; Ardeshir Hanifi; Dan Henningson; Anatoli Tumin; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Receptivity; three-dimensional boundary layers; optimal growth; adjoint solutions; swept wing;

    Sammanfattning : This thesis deals with receptivity mechanisms of three-dimensional, crossflow-dominated boundary layers. The receptivity of two model problems, a swept-flat-plate and a swept-wing boundary layer, is investigated by solving the parabolised stability equations (PSE) as well as by performing direct numerical simulations (DNS). LÄS MER