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Non-Spherical Particle Interaction in Duct and Jet Flow

Hazim, Ammar (författare)
Luleå tekniska universitet,Strömningslära och experimentell mekanik
Mandø, Matthias, Associate Professor (opponent)
Dept of Energy Technology, Aalborg University, Esbjerg, Denmark
 (creator_code:org_t)
ISBN 9789175833989
Luleå : Luleå tekniska universitet, 2015
Engelska 158 s.
Serie: Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, 1402-1544
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)
Abstract Ämnesord
Stäng  
  • Wood waste is the most popular biomass recourse for many nations. Burned wood can, direct or indirect, release one of the greenhouse gases, carbon dioxide. The process can still be seen as a renewable source of energy since replanting of the trees and crops are consuming nearly the same amount of carbon dioxide through photosynthesis. Thermal gasification is one of the efficient methods to utilize energy from wood waste. Products from the component of concern can be used for direct energy production like in boilers and gas turbines or indirectly via dimethyl ether (DME), for instance. The physics of gasification is complex and several issues can influence the process. There is a lack of knowledge of several phenomena, some of which are related to solid-gas flow in the gasifier and in the premixed feeding pipelines. One such area is mechanisms related to turbulence modulation in the presence of spherical and non-spherical particles and how much the flow can disturb the motion of the particles. This is studied in the present thesis and the motion of the particles in different flow field is disclosed. At the moment there is no agreement in the scientific community on a single dimensionless number that can safely describe the influence of spherical particles in turbulent flow. For non-spherical particles additional levels of freedom are introduced and the dependence on drag and lift from the orientation of the particles as a function of Reynolds number adds to the complexity.Based on a literature review a fundamental experimental study is carried out in simple flow field geometry, a 2D duct flow. The aim is to reveal the influence of spherical glass particle on the turbulent flow field in the core and near wall flows. Additional studies with wood particles gave more information about how real biomass particles affect the turbulence as compared to spherical ones. Next the instantaneous distribution of biomass particles was studied experimentally. It is known that this distribution significantly influences the soot formation in a gasifier. Two different techniques of flow control were studied, swirling flow and synthetic jet flow. Particles shape and inertia and the strength of vortices and vortices interaction in coaxial jets and swirling jet flow were studied and yielded a high influence on the preferential concentration of particles as well as on the root mean square values for velocity in coaxial jets flow. The synthetic jet add momentum to the flow without disturbing the mass loading ratio and result in higher dispersion of the particles away from the centreline of the jet.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Strömningsmekanik och akustik (hsv//swe)
ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Fluid Mechanics and Acoustics (hsv//eng)

Nyckelord

Solid-gas flow
turbulence modulation
duct flow
coaxial jets flow
swirl jet flow
active flow control
synthetics jet
biomass powder
non-spherical particles
PIV measurement
Strömningslära
Fluid Mechanics

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Hazim, Ammar
Mandø, Matthias, ...
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TEKNIK OCH TEKNOLOGIER
TEKNIK OCH TEKNO ...
och Maskinteknik
och Strömningsmekani ...
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Doctoral thesis ...
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Luleå tekniska universitet

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