| 1. |
- Ahadi, Aylin, et al.
(författare)
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Simulation of a Friction Stir Welding Process using FE technique
- 2006
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Ingår i: Report TVSM. - 0281-6679.
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Konferensbidrag (refereegranskat)abstract
- In this paper a three dimensional FE model of the friction stir welding (FSW) is presented and the FSW process is simulated. The model has been implemented in FE code Abaqus with user subroutines DLOAD, DFLUX and UMASFL. The material data used to describe the welded panels is from an aluminium alloy called AL-2024-T3 and the material is assumed to be isotropic with temperature dependent yield stress and elastic modulus. A nonlinear-coupled thermo-mechanical analysis was performed in order to study the temperature and stress distribution.
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| 2. |
- Alenius, Emma, 1983-, et al.
(författare)
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LES of acoustic-flow interaction at an orifice plate
- 2012
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Ingår i: 18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference). - Reston, Virigina : American Institute of Aeronautics and Astronautics Inc.. - 9781600869327
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Konferensbidrag (refereegranskat)abstract
- The scattering of plane waves by a thick orifice plate, placed in a circular or square duct with ow, is studied through Large Eddy Simulation. The scattering matrix is computed and compared to measurements, showing reasonably good agreement except around one frequency (St ≈ 0:4). Here a stronger amplification of acoustic energy is observed in the circular duct simulations than in the measurements and the square duct simulations. In order to improve the understanding of the interaction between an incoming wave, the flow, and the plate, a few frequencies are studied in more detail. A Dynamic Mode Decomposition is performed to identify flow structures at significant frequencies. This shows that the amplification of acoustic energy occurs at the frequency where the jet in the circular duct has an axisymmetric instability. Furthermore, the incoming wave slightly amplifies this instability, and suppresses background flow fiuctuations.
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| 3. |
- Alenius, Emma, et al.
(författare)
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Scattering of Plane Waves by a Constriction
- 2011
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Ingår i: Proceedings of ASME Turbo Expo 2011, Vol 7, Parts A-C. - : American Society Of Mechanical Engineers. - 9780791854679 ; , s. 1043-1052
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Konferensbidrag (refereegranskat)abstract
- Liner scattering of low frequency waves by an orifice plate has been studied using Large Eddy Simulation and an acoustic two-port model. The results have been compared to measurements with good agreement for waves coming from the downstream side. For waves coming from the upstream side the reflection is over-predicted, indicating that not enough of the acoustic energy is converted to vorticity at the upstream edge of the plate. Furthermore, the sensitivity to the amplitude of the acoustic waves has been studied, showing difficulties to simultaneously keep the amplitude low enough for linearity and high enough to suppress flow noise with the relatively short times series available in LES.
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| 8. |
- Arlov, Dragana, et al.
(författare)
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Large eddy simulation of an aerated Rushton stirred tank
- 2006
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Konferensbidrag (refereegranskat)abstract
- Simulations of aerated stirred reactor is performed using Large Eddy Simulation (LES). The gas phase is modelled using Lagrangian Particle Tracking (LPT). The reactor is stirred by a single impeller Rushton turbine, centred in the reactor. The air is introduced at the bottom wall through a circular sparger. The main focus is to investigate how the gas phase affects the liquid in the reactor. Effects of gas volume flow and stirrer speed are investigated. The results show that the time averaged liquid velocities in the radial and tangential directions as well as the pumping capacity decrease with increasing gas volume fraction. In the axial direction the gas redirects the radial jet upwards breaking the symmetry of the ring vortices.
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| 9. |
- Arlov, Dragana, et al.
(författare)
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Numerical simulation of a gas-liquid Rushton stirred reactor - LES and LPT
- 2008
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Ingår i: Computers & Fluids. - : Elsevier BV. - 0045-7930 .- 1879-0747. ; 37:7, s. 793-801
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Konferensbidrag (refereegranskat)abstract
- Simulations of aerated stirred reactor is performed using a combination of large eddy simulation (LES) and Lagrangian particle tracking (LPT). A single impeller Rushton turbine is positioned at the center of the reactor and air is introduced at the bottom through a circular sparger. Effects of the gas volume flow, stirrer speed and sparger dimension are investigated. The results show that the time averaged liquid velocities in radial and tangential directions decrease with increasing gas volume fraction. In the axial direction, the gas redirects the radial jet upwards, breaking the symmetry of the ring vortices. Especially, for a narrower sparger, a more concentrated tilt upwards is observed with a larger region of negative axial velocity. Although, low aeration number is used, the periodicity from the impeller is decreasing and interfering with the creation of the trailing vortex pair. The gas dispersion increases with decreasing the sparger diameter.
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