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- Hosseini, Seyed Mohammad, et al.
(författare)
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Study of Flame Dynamics and Flashback Mechanism in a Gas Turbine Combustor Using Simultaneous OH-PLIF and PIV
- 2010
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Ingår i: AIAA 2010-6668. - Reston, Virigina : American Institute of Aeronautics and Astronautics.
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Konferensbidrag (refereegranskat)abstract
- The present study aims to investigate the effects of burner geometry on flame characteristics, stabilization, and the occurrence of flashback using the Triple Annular Research Swirler (TARS). A premixing tube is placed at the exit of the burner. Simultaneous Planar Laser Induced Fluorescence (PLIF) of OH radicals indicating the reacting zone and Particle Image Velocimetry (PIV) for flow field mapping, were applied to study the flow- and flame-dynamics during transition from flame stabilized in the combustion chamber to flame flashback in the mixing tube. Particular attention was placed on the flame behavior/dynamics near the lean blow out (LBO). The flow field featured a central recirculation zone (CRZ), and an annular swirling jet with internal and external shears layers. The movement of the flame front relative to the upstream stagnation point of the vortex breakdown at different conditions was studied. Simultaneous planar measurements using laser diagnostics, namely, Planar Laser Induced Fluorescence (PLIF) of OH radicals and Particle Image Velocimetry (PIV), have been carried out. With mixing tube and at lean cases, vortex breakdown and the flame holding occurred close to the tube exit. As the equivalence ratio was increased, the flame entered intermittently into the premixing tube. Increasing further the equivalence ratio, the flame was stabilized inside the premixing tube. Different statistical evaluations were performed on the data to obtain better understanding of the flame stabilization mechanism. They included PDF of the axial velocity, mean velocity field and mean intensity of the OH radical, two-dimensional correlation between PIV and LIF data, POD analysis of the velocity vectors, distribution of OH radical intensity and binary images of density distribution of the seeding particles.
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| 2. |
- Iudiciani, Piero, et al.
(författare)
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Proper Orthogonal Decomposition for experimental investigation of swirling flame instabilities
- 2010
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Ingår i: Paper AIAA 2010-584. - Reston, Virigina : American Institute of Aeronautics and Astronautics.
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Konferensbidrag (refereegranskat)abstract
- An experimental investigation of both confined and unconfined flames on a Triple Annular Research Swirler (TARS) is presented. The paper focuses on post-processing techniques aiming at extracting information on the dynamics that are lost through classical statistics approach. POD together with a derived a-posteriori phase averaging procedure successfully reconstructed the dynamics of flames under thermo-acoustic instabilities in the confined case. For unconfined flames, an analysis of the azimuthal modes is performed.
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| 5. |
- Al Sam, Ali, et al.
(författare)
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The effect of moving waves on neutral marine atmospheric boundary layer
- 2014
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Ingår i: First Symposium on OpenFOAM® in Wind Energy. - : EDP Sciences. ; 2:01003
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Konferensbidrag (refereegranskat)abstract
- Large eddy simulations are performed to study the effects of wind-wave direction misalignment of the neutral marine atmospheric boundary layer over a wavy wall. The results show that the wind-wave misalignment has a significant effect on the velocity profiles and the pressure fluctuation over the wave surface. These effects are not confined to the near wave surface region but extend over the whole atmospheric surface layer.
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| 8. |
- Grosshans, Holger, et al.
(författare)
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Development of an efficient statistical volumes of fluid-Lagrangian particle tracking coupling method
- 2014
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Ingår i: International Journal for Numerical Methods in Fluids. - : Wiley. - 1097-0363 .- 0271-2091. ; 74:12, s. 898-918
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Tidskriftsartikel (refereegranskat)abstract
- The breakup of a liquid jet into irregular liquid structures and droplets leading to the formation of a dilute spray has been simulated numerically. To overcome the shortcomings of certain numerical methods in specific flow regimes, a combined approach has been chosen. The intact liquid core, its primary breakup and the dense spray regime are simulated using the volumes of fluid (VOF) method in combination with LES, whereas the Lagrangian particle tracking (LPT) approach in the LES context is applied to the dilute spray regime and the secondary breakup of droplets. A method has been developed to couple both simulation types on a statistical basis. This statistical coupling approach (SCA) reflects the dominating physical mechanisms of the two-phase flow in each regime to a high degree. The main benefit of the SCA is computational efficiency as compared with the more straightforward approach where one follows each structure, denoted here as the direct coupling approach. The computational benefits stem from the reduction of computational time since the VOF simulation is run only until statistical convergence and not during the whole spray development. A second benefit using the SCA is the possibility to use the stochastic parcel method in the LPT simulation whereby a large number of droplets may be handled. The coupling approach is applied to the atomization of a fuel jet in a high pressure chamber, demonstrating the gain of efficiency of the SCA as compared with direct coupling approach. Copyright © 2014 The Authors. International Journal for Numerical Methods in Fluids published by John Wiley & Sons Ltd.
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