Sökning: "optimal forcing"

Visar resultat 1 - 5 av 25 avhandlingar innehållade orden optimal forcing.

  1. 1. Reduction of Aerodynamic Forcing inTransonic Turbomachinery : Numerical Studies on Forcing Reduction Techniques

    Författare :Florian Fruth; Torsten Fransson; Damian Vogt; Ronald Mailach; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Forced Response; Aerodynamic Forcing; Efficiency; Blade Count Ratio; Clocking;

    Sammanfattning : Due to more and more aggressive designs in turbomachinery, assuring the structural integrity of its components has become challenging. Also influenced by this trend is blade design, where lighter and slimmer blades, in combination with higher loading, lead to an increased risk of failure, e.g. in the form of blade vibration. LÄS MER

  3. 2. Studies on instability and optimal forcing of incompressible flows

    Författare :Mattias Brynjell-Rahkola; Dan S. Henningson; Ardeshir Hanifi; Philipp Schlatter; François Gallaire; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; hydrodynamic stability; optimal forcing; resolvent operator; Laplace preconditioner; spectral element method; eigenvalue problems; inverse power method; direct numerical simulations; Falkner–Skan–Cooke boundary layer; localized roughness; crossflow vortices; Blasius boundary layer; localized suction; helical vortices; lid-driven cavity; cylinder flow; Teknisk mekanik; Engineering Mechanics;

    Sammanfattning : This thesis considers the hydrodynamic instability and optimal forcing of a number of incompressible flow cases. In the first part, the instabilities of three problems that are of great interest in energy and aerospace applications are studied, namely a Blasius boundary layer subject to localized wall-suction, a Falkner–Skan–Cooke boundary layer with a localized surface roughness, and a pair of helical vortices. LÄS MER

  4. 3. Towards Optimal Real-Time Automotive Emission Control

    Författare :Jonathan Lock; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; dynamic programming; optimal control methods; hybrid vehicles; three way catalyst modelling; Automotive emissions control;

    Sammanfattning : The legal bounds on both toxic and carbon dioxide emissions from automotive vehicles are continuously being lowered, forcing manufacturers to rely on increasingly advanced methods to reduce emissions and improve fuel efficiency. Though great strides have been made to date, there is still a large potential for continued improvement. LÄS MER

  5. 4. Global stability analysis of three-dimensional boundary layer flows

    Författare :Mattias Brynjell-Rahkola; Dan Henningson; Philipp Schlatter; Ardeshir Hanifi; Spencer Sherwin; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Hydrodynamic stability; transition to turbulence; global analysis; boundary layers; roughness; laminar flow control; Stokes Laplace preconditioner; optimal forcing; crossflow vortices; Ginzburg-Landau; Falkner-Skan-Cooke; Blasius; lid-driven cavity;

    Sammanfattning : This thesis considers the stability and transition of incompressible boundary layers. In particular, the Falkner–Skan–Cooke boundary layer subject to a cylindrical surface roughness, and the Blasius boundary layer with applied localized suction are investigated. LÄS MER

  7. 5. 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