Sökning: "vibrationer"

Visar resultat 11 - 15 av 118 avhandlingar innehållade ordet vibrationer.

1. 11. Modelling of compaction of metal powder and damage accum ulation due to fatigue in powder materials

   Författare :Joakim Cedergren; Mekanik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; hydraulik; vakuumteknik; vibrationer; akustik; Maskinteknik; hydraulics; Mechanical engineering; friction; FEM; numerical modelling; continuum mechanics; fatigue loading; powder compaction; vacuum technology; vibration and acoustic engineering;

   Sammanfattning : This thesis addresses powder manufactured (P/M) components, with special attention to the compaction process and to the sensitivity to damage accumulation due to fatigue within powder compacted specimens. Three dimensional simulations of the compaction process have been performed, using an explicit dynamic dilatant finite strain finite element code supplemented with the effects from contact friction within the die, modelled by Coulomb friction. LÄS MER

3. 12. In-Cylinder Fluid Flow, Fuel Preparation and Combustion in SI Engines - Application of Optical Diagnostics

   Författare :Martin Ekenberg; Förbränningsmotorer; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Laserteknik; vakuumteknik; vibrationer; akustik; Motors and propulsion systems; Motorer; hydraulik; Maskinteknik; PIV; vibration and acoustic engineering; hydraulics; vacuum technology; Mechanical engineering; framdrivningssystem; Laser technology;

   Sammanfattning : In this thesis laser-based measurements of in-cylinder flow and fuel concentrations in two stroke and direct injected four-stroke engines are presented. The major problem with the carburetted two-stroke engine is the short-circuiting of fuel that occurs during the scavenging phase. This leads to large emissions of unburned hydrocarbons. LÄS MER

4. 13. Large Eddy Simulation of Turbulent Flows in Combustor Related Geometries

   Författare :Jessica Gullbrand; Institutionen för energivetenskaper; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Mechanical engineering; Energiforskning; Energy research; Cartesian grid; high order wall treatment; SGS models; turbulence; subgrid scale models; LES; Large Eddy Simulation; akustik; vibrationer; vakuumteknik; hydraulik; vibration and acoustic engineering; Maskinteknik; vacuum technology; hydraulics;

   Sammanfattning : Numerical simulations using Large Eddy Simulation (LES) are applied to turbulent swirling flow fields. The swirling motion is often introduced into combustors to act as flame holders or enhance the mixing between species. Different turbulence models capture the swirling motion more or less accurately. LÄS MER

5. 14. Numerical Modelling of Dynamics of Light Porous Materials

   Författare :Peter Göransson; Teknisk akustik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Mechanical engineering; glass fibre; foam; material characterisation; elasto-acoustic; fluid-structure interaction; finite element; Biot; porous material; hydraulics; vacuum technology; vibration and acoustic engineering; Maskinteknik; hydraulik; vakuumteknik; vibrationer; akustik;

   Sammanfattning : Porous materials are among the most commonly used materials for noise and vibration reduction in modern transportation vehicles. To design, industrially relevant, weight and cost effective noise and vibration measures, there is a need for general prediction models capable of representing the elasto-acoustic behaviour of such materials. LÄS MER

7. 15. Large Eddy Simulations of Separated Compressible Flows around Wing Sections

   Författare :Jörgen Held; Strömningsteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; turbulence; subgrid-scale; shock-boundary layer interaction; wing section; transonic; subsonic; compressible; separated; Large eddy simulation; LES; PVM; Mechanical engineering; hydraulics; vacuum technology; vibration and acoustic engineering; Maskinteknik; hydraulik; vakuumteknik; vibrationer; akustik;

   Sammanfattning : This thesis concerns numerical calculations of compressible separated flows, with and without shocks, around wing sections using Large Eddy Simulations (LES). The considered geometries are the NACA 0012 wing section and the ONERA AT15A wing section. LÄS MER