Search for dissertations about: "vortical flow structures"

Showing result 1 - 5 of 16 swedish dissertations containing the words vortical flow structures.

  1. 1. Numerical investigation of the flow and instabilities at part-load and speed-no-load in an axial turbine

    Author : Jelle Kranenbarg; Michel Cervantes; Lisa Prahl Wittberg; Luleå tekniska universitet; []
    Keywords : ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Speed-no-load; vortical flow structures; flow instabilities; rotating stall; mitigation; independent guide vanes; axial turbine; swirling flow; off design operation; URANS; parametric study; blade clearance; head losses; diffusor; GEKO model; flow separation; hydraulic turbine; Strömningslära; Fluid Mechanics;

    Abstract : Global renewable energy requirements rapidly increase with the transition to a fossil-free society. As a result, intermittent energy resources, such as wind- and solar power, have become increasingly popular. However, their energy production varies over time, both in the short- and long term. READ MORE

  2. 2. Vortices in turbulent curved pipe flow-rocking, rolling and pulsating motions

    Author : Athanasia Kalpakli Vester; P. Henrik Alfredsson; Ramis Örlü; Nils Tillmark; Knud Meyer; KTH; []
    Keywords : Turbulence; curved pipes; swirling flow; pulsatile flow; time-resolved stereoscopic particle image velocimetry; hot-wire anemometry; proper orthogonal decomposition; turbocharger;

    Abstract : This thesis is motivated by the necessity to understand the flow structure of turbulent flows in bends encountered in many technical applications such as heat exchangers, nuclear reactors and internal combustion engines. Flows in bends are characterised by strong secondary motions in terms of counter-rotating vortices (Dean cells) set up by a centrifugal instability. READ MORE

  3. 3. Experimental study of turbulent flows through pipe bends

    Author : Athanasia Kalpakli; P. Henrik Alfredsson; Ramis Örlü; Christoph Brücker; KTH; []
    Keywords : ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Turbulent flow; swirl; pulsation; pipe bend; hot-wire anemometry; cold-wire anemometry; laser Doppler velocimetry; stereoscopic particle image velocimetry.;

    Abstract : This thesis deals with turbulent flows in 90 degree curved pipes of circular cross-section. The flow cases investigated experimentally are turbulent flow with and without an additional motion, swirling or pulsating, superposed on the primary flow. READ MORE

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

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

    Abstract : 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. READ MORE

  5. 5. Utilization of Decomposition Techniques for Analyzing and Characterizing Flows

    Author : Christian Carlsson; Strömningsteknik; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Decomposition techniques; Proper orthogonal decomposition; Dynamic mode decomposition; Extended dynamic mode decomposition; Swirl switching; Swirling flow; Low swirl burner; Fluid-structure interaction;

    Abstract : This thesis presents the utilization of two different decomposition techniques, proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD), for enhanced understanding of flow structures and their stability. The advantages of these techniques are shown for a range of flow situations, most of which are turbulent. READ MORE