Sökning: "boundary-layer blowing"

Visar resultat 1 - 5 av 10 avhandlingar innehållade orden boundary-layer blowing.

  1. 1. Experimental study on turbulent boundary-layer flows with wall transpiration

    Författare :Marco Ferro; Jens Fransson; Bengt Fallenius; Joseph Klewicki; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Turbulent boundary layer; boundary-layer suction; boundary-layer blowing; wall-bounded turbulent flows; self-sustained turbulence; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : Wall transpiration, in the form of wall-normal suction or blowing through a permeable wall, is a relatively simple and effective technique to control the behaviour of a boundary layer. For its potential applications for laminar-turbulent transition and separation delay (suction) or for turbulent drag reduction and thermal protection (blowing), wall transpiration has over the past decades been the topic of a significant amount of studies. LÄS MER

  3. 2. Optimisation and control of boundary layer flows

    Författare :Antonios Monokrousos; Dan S. Henningson; Per Lötstedt; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; boundary layer; control; estimation; optimal disturbances; Lagrange method; Engineering mechanics; Teknisk mekanik;

    Sammanfattning : Both optimal disturbances and optimal control are studied by means of numerical simulations for the case of the flat-plate boundary-layer flow. The optimisation method is the Lagrange multiplier technique where the objective function is the kinetic energy of the flow perturbations and the constraints involve the linearised Navier–Stokes equations. LÄS MER

  4. 3. Flow control of boundary lagers and wakes

    Författare :Jens H. M. Fransson; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Laminar-turbulent transition; asymptotic suction boundary layer; free stream turbulence; Tollmien-Schlichting wave; stability; flow control; cylinder wake; Engineering mechanics; Teknisk mekanik;

    Sammanfattning : Both experimental and theoretical studies have beenconsidered on flat plate boundary layers as well as on wakesbehind porous cylinders. The main thread in this work iscontrol, which is applied passively and actively on boundarylayers in order to inhibit or postpone transition toturbulence; and actively through the cylinder surface in orderto effect the wakecharacteristics. LÄS MER

  5. 4. Experimental design and vortex analyses in turbulent wake flows

    Författare :Bengt E. G. Fallenius; Jens H. M. Fransson; Henrik Alfredsson; Marianna Braza; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; bluff bodies; wake flow; experimental design; vortex detection; flow control; asymptotic suction boundary layer;

    Sammanfattning : A new experimental setup for studies on wake flow instability and its control that successfully has been designed and manufactured, is introduced and de- scribed. The main body is a dual-sided flat plate with an elliptic leading edge and a blunt trailing edge. LÄS MER

  7. 5. Investigations of Flow Conditions in an Automotive Wind Tunnel

    Författare :Emil Ljungskog; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Wind tunnel; Ground simulation; Tangential blowing; CFD simulations; Slotted walls;

    Sammanfattning : As vehicle manufacturers seek to shorten the development time of new models, wind tunnel testing of prototype vehicles needs to be partially replaced by virtual simulations. However, this requires thorough validation of the virtual methods, which is done by comparison to wind tunnel tests. LÄS MER