| 1. |
- Kehoe, Laura, et al.
(författare)
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Make EU trade with Brazil sustainable
- 2019
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 364:6438, s. 341-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 2. |
- Parra-Santos, Teresa, et al.
(författare)
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Acoustic Instabilities on Swirling Flames
- 2013
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Ingår i: International Journal of Mechanical, Industrial Science and Engineering. ; 7:9, s. 61-64
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Tidskriftsartikel (refereegranskat)
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| 3. |
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| 4. |
- Parra-Santos, Teresa, et al.
(författare)
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An isothermal analysis of curved-vane and flat-vane swirlers for burners
- 2015
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Ingår i: Engineering Computations. - 0264-4401. ; 32:3, s. 668-686
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Tidskriftsartikel (refereegranskat)abstract
- Purpose - One current trend in burner technology is to obtain high efficiency while keeping low levels of NOx emissions. A swirling flow in combustion ensures a fixed position of a compact flame. Therefore, it is necessary to design efficient swirlers. Flow patterns are simulated for the different swirl devices proposed in this work. Two axial-swirlers are studied: one based on curve-vanes consisting of a straight line with an arc of a circle as the trailing edge and the other is the common flat-vanes. The purpose of this paper is to assess the accuracy of different swirl generators using a well-known benchmark test case. Design/methodology/approach - This work deals with modelling the swirler using two approaches: the general purpose Computational fluid dynamics (CFD) solver Ansys-Fluent (R) and the suite of libraries OpenFOAM (R) to solve the Reynolds Averaged Navier Stokes equations, showing there is a slight deviation between both approaches. Their performance involves analyzing not only the Swirl number but also the size of the recirculation zones in the test chamber. A subsequent process on the flow patterns was carried out to establish the intensity of segregation which provides insight into the quality of mixing. Findings - CFD models are feasible tools to predict flow features. It was found that numerical results tend to reduce the inner recirculation zone (IRZ) radial size. Further, an increase of the swirl number involves larger IRZ and a smaller outer recirculation zone (ORZ). The curved swirler displays a better axi-symmetric behaviour than flat vanes. There is weak influence of the chord vanes on the swirl number. The number of vanes is a compromise of head loses and guidance of the flow. Originality/value - The paper offers two different approaches to solve turbulent swirling flows. One based in a general contrasted commercial tool and other using open source code. Both models show similar performance. An innovative set up for an axial swirler different from the conventional flat vanes was proposed.
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| 5. |
- Parra-Santos, Teresa, et al.
(författare)
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Implicit les applied to isothermal swirling coaxial jets
- 2016
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Ingår i: Symposia: Turbomachinery Flow Simulation and Optimization; Applications in CFD; Bio-Inspired and Bio-Medical Fluid Mechanics; CFD Verification and Validation; Development and Applications of Immersed Boundary Methods; DNS, LES and Hybrid RANS/LES Methods; Fluid Machinery; Fluid-Structure Interaction and Flow-Induced Noise in Industrial Applications; Flow Applications in Aerospace; Active Fluid Dynamics and Flow Control - Theory, Experiments and Implementation. - 9780791850282 ; 1A-2016
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Konferensbidrag (refereegranskat)abstract
- This work is devoted to the analysis of the interaction of two coaxial jet with swirling flow using Large Eddy Simulation methodology to reproduce the case of Roback and Johnson. The eight - flat - vanes in the annular nozzle are the precursor of the swirling annular jet with high swirl number. An implicit LES model was used, this model uses mesh size as filter width so no sub-grid model is required. It is the numerical error who plays the role of dissipative part of the stress tensor in the sub-mesh. Mesh prerequisites are Ay+ = 1 and uniform hexahedral mesh. The resolution scheme used is a Total Variation Diminishing (TVD) with coefficients looking for good precision. PISO is the pressure-velocity coupling used. Besides, multigrid resolution improves the performance towards the full convergence. Influence of the swirl number on the flow pattern is analyzed. Also the impact of conical diffuser on the mixing is presented.
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| 6. |
- Parra-Santos, Teresa, et al.
(författare)
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Numerical modelling of swirling diffusive flames
- 2016
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Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 114
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Tidskriftsartikel (refereegranskat)abstract
- Computational Fluid Dynamics has been used to study the mixing and combustion of two confined jets whose setup and operating conditions are those of the benchmark of Roback and Johnson. Numerical model solves 3D transient Navier Stokes for turbulent and reactive flows. Averaged velocity profiles using RNG swirl dominated k-epsilon model have been validated with experimental measurements from other sources for the non reactive case. The combustion model is Probability Density Function. Bearing in mind the annular jet has swirl number over 0.5, a vortex breakdown appears in the axis of the burner. Besides, the sudden expansion with a ratio of 2 in diameter between nozzle exits and the test chamber produces the boundary layer separation with the corresponding torus shape recirculation. Contrasting the mixing and combustion models, the last one produces the reduction of the vortex breakdown.
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| 7. |
- Parra-Santos, Teresa, et al.
(författare)
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Swirl influence on mixing and reactive flows
- 2016
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Ingår i: Symposia: Fluid Mechanics (Fundamental Issues and Perspectives; Industrial and Environmental Applications); Multiphase Flow and Systems (Multiscale Methods; Noninvasive Measurements; Numerical Methods; Heat Transfer; Performance); Transport Phenomena (Clean Energy; Mixing; Manufacturing and Materials Processing); Turbulent Flows - Issues and Perspectives; Algorithms and Applications for High Performance CFD Computation; Fluid Power; Fluid Dynamics of Wind Energy; Marine Hydrodynamics. - 9780791850299 ; 1B-2016
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Konferensbidrag (refereegranskat)abstract
- The interaction of two confined coaxial jets has been studied using Computational Fluid Dynamics. Annular jet flows over 8 flat blade swirl generator. Numerical simulation uses RNG k- ϵ turbulence model. These models are suitable for turbulent swirl dominated flows. Intermediate swirl injector has been simulated and the flow patterns for non-reactive and reactive cases are contrasted. Low swirling injectors do not promote the fluid to turn over near the center of the chamber, resulting larger mixing zones with weak gradients. Whereas large swirling flows promote the formation of an Inner Recirculation Zone that is a precursor of higher gradients. Probability Density Function is selected as combustion model. High swirl numbers let fix the location of the reactive zone.
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