| 1. |
- Karlsson, G., et al.
(författare)
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Numerical study of heat transfer, flow fields, turbulent length scales, and anisotropy in corrugated heat exchanger channels
- 2022
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Ingår i: Physics of Fluids. - : AIP Publishing. - 1070-6631 .- 1089-7666. ; 34:5
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we report on large eddy simulation (LES) of convectively dominated heat transfer in a corrugated heat exchanger channel using the computational fluid dynamics toolbox, OpenFOAM. A chevron pattern domain with 63 contact points is used to represent the conditions in a real plate heat exchanger (PHE). The unsteady nature of the flow is elucidated using visualization techniques based on volume rendering of temperature and iso surfaces of vorticity defined using the λ2-criterion and contours of wall shear stress and wall heat flux to illustrate the heat transfer process. Global surface averaged temperature and pressure drop are extracted from the LES on successively finer grids, approaching direct numerical simulation resolution, to increase the understanding of grid resolution requirements for LES in PHEs. Industry standard Reynolds-averaged Navier-Stokes simulations are compared to the LES results along selected profiles to demonstrate similarities and differences between the two techniques. The differences detected are further investigated using anisotropy invariant mapping, energy spectra, and turbulence length scale distributions. Significant differences between the model classes are detected and detailed. Moreover, the LES resolution requirements for the flow and the heat transfer processes are found to be different with the latter being more severe.
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| 2. |
- Zettervall, N., et al.
(författare)
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LES of Combustion Dynamics in an Ethylene-Hydrogen-Air Ramjet
- 2022
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Ingår i: 33rd Congress of the International Council of the Aeronautical Sciences, ICAS 2022. - 9781713871163 ; 7, s. 4903-4919
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Konferensbidrag (refereegranskat)abstract
- A combustion Large Eddy Simulation (LES) is used to examine the flow, mixing, fuel-injection and combustion dynamics of a ramjet combustor with a cavity flame holder. The combustor is a running 50/50, in mole, ethylene/hydrogen fuel mixture. A direct-connect facility dual-mode ramjet/scramjet combustor presents the target case, with in the literature available experimental data is used in the present study for validation of the current LES results. Experimental data for time-averaged chemiluminescence, represented by the CH* signal, and CH-PLIF and OH-PLIF, are used to validate the LES. The LES, using a compact 66-step reaction mechanism for the ethylene/hydrogen/air combustion, predicts a highly dynamic combustion behavior, where the flame oscillates between longer sequences in a cavity stabilized state and shorter ones with a jet-wake stabilized state. A volume averaging in cross-section slabs along the combustor length, plotted over time, is used to further examine and visualize the dynamic combustion and the effects of the dynamics on the temperature, pressure, heat release and axial velocity. Such cross-section slabs, and constant volume simulations, is used to further investigate the predictive effect of the accumulation of H2O2 on the combustion dynamics and the sudden increases in flame size associated with the dynamic flame behavior.
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| 3. |
- Bai, X. S., et al.
(författare)
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Closing Remarks
- 2022
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Ingår i: Advanced Turbulent Combustion Physics and Applications. - : Cambridge University Press. ; , s. 460-463
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 4. |
- Cappelletto, Elia, et al.
(författare)
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Impact of Post Manufacturing Handling of Protein-Based Biologic Drugs on Product Quality and User Centricity
- 2024
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Ingår i: Journal of Pharmaceutical Sciences. - : Elsevier B.V.. - 0022-3549 .- 1520-6017.
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Forskningsöversikt (refereegranskat)abstract
- This article evaluates the current gaps around the impact of post-manufacturing processes on the product qualities of protein-based biologics, with a focus on user centricity. It includes the evaluation of the regulatory guidance available, describes a collection of scientific literature and case studies to showcase the impact of post-manufacturing stresses on product and dosing solution quality. It also outlines the complexity of clinical handling and the need for communication, and alignment between drug providers, healthcare professionals, users, and patients. Regulatory agencies provide clear expectations for drug manufacturing processes, however, guidance supporting post-product manufacturing handling is less defined and often misaligned. This is problematic as the pharmaceutical products experience numerous stresses and processes which can potentially impact drug quality, safety and efficacy. This article aims to stimulate discussion amongst pharmaceutical developers, health care providers, device manufacturers, and public researchers to improve these processes. Patients and caregivers' awareness can be achieved by providing relevant educational material on pharmaceutical product handling.
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| 5. |
- Cappelletto, Elia, et al.
(författare)
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Impact of Post Manufacturing Handling of Protein-Based Biologic Drugs on Product Quality and User Centricity
- 2024
-
Ingår i: Journal of Pharmaceutical Sciences. - : Elsevier. - 0022-3549 .- 1520-6017.
-
Tidskriftsartikel (refereegranskat)abstract
- This article evaluates the current gaps around the impact of post-manufacturing processes on the product qualities of protein-based biologics, with a focus on user centricity. It includes the evaluation of the regulatory guidance available, describes a collection of scientific literature and case studies to showcase the impact of post-manufacturing stresses on product and dosing solution quality. It also outlines the complexity of clinical handling and the need for communication, and alignment between drug providers, healthcare professionals, users, and patients. Regulatory agencies provide clear expectations for drug manufacturing processes, however, guidance supporting post-product manufacturing handling is less defined and often misaligned. This is problematic as the pharmaceutical products experience numerous stresses and processes which can potentially impact drug quality, safety and efficacy. This article aims to stimulate discussion amongst pharmaceutical developers, health care providers, device manufacturers, and public researchers to improve these processes. Patients and caregivers' awareness can be achieved by providing relevant educational material on pharmaceutical product handling.
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| 6. |
- Fureby, C., et al.
(författare)
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Large-Eddy Simulation of Supersonic Combustion in a Mach 2 Cavity-Based Model Scramjet Combustor
- 2024
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Ingår i: AIAA SciTech Forum and Exposition, 2024. - 9781624107115
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Konferensbidrag (refereegranskat)abstract
- In this study we report on reactive Large Eddy Simulations (LES) of flow and combustion in the US Air Force Research Laboratory Research Cell 19 cavity-based scramjet combustor. This case involves combustion of ethylene that is injected into a cavity. It has previously been studied experimentally with multiple techniques as well as numerically using hybrid RANS/LES. Here, we build on the existing knowledge and provide an in-depth investigation of the flow and combustion by use of a pure LES approach. A range of fuel injection rates are studied as well as the non-reacting case. This way we can disseminate how different amounts of combustion, and the associated volumetric expansion, in the cavity affects the shear-layer above the cavity, the recirculation zone, and the downstream shock-train. For example, an additional shock-train emerges from the start of the cavity when combustion is present, and it grows in intensity with increasing fueling rate from 50 to 110 slpm. For the cases studied, good agreement is found between simulations, LES, and experiments, Particle Image Velocimetry (PIV), Hyperspectral Imagining (HsI) and Laser Induced Breakdown Spectroscopy (LIBS). More specifically, the primary flow features, such as the shock train, primary and secondary cavity recirculation regions, and shear-layer lift due to exothermicity, are found to evolve similarly with increasing fueling rate in the experiments and the LES which enables using the more complete LES result to further investigate the flow and combustion physics.
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| 7. |
- Fureby, C.
(författare)
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Subgrid models, reaction mechanisms, and combustion models in large-eddy simulation of supersonic combustion
- 2021
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Ingår i: AIAA Journal. - 0001-1452. ; 59:1, s. 215-227
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Tidskriftsartikel (refereegranskat)abstract
- Here, we report on large-eddy simulation (LES) of supersonic flow, mixing, self-ignition, and combustion in a model scramjet combustor. The combustor has been experimentally investigated at DLR, German Aerospace Center Lampoldshausen and consists of a one-sided divergent channel with a wedge-shaped flame-holder: at the base of which, hydrogen is injected. This combustor has been extensively studied by many research groups and constitutes a good validation case for model development and physics elucidation. The LES model used is based on an unstructured finite volume discretization of the filtered mass, momentum, species, and energy equations, as well as an explicit flow solver. Three subgrid flow models, three reaction mechanisms, and three LES combustion models are employed to examine the sensitivity to these modeling parameters. The LES predictions are compared with experimental data for velocity, temperature, wall pressure at different cross sections, as well as schlieren and OH chemiluminesence images, showing good agreement for both first-and second-order statistics, as well as the instantaneous flow structures. Furthermore, these LES results are used to illustrate and explain the intrinsic flow, mixing, and combustion features of this combustor. The intrinsic relationship between the different modeling parameters is also discussed.
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| 8. |
- Nilsson, E. J.K., et al.
(författare)
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Chemical Kinetics
- 2022
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Ingår i: Advanced Turbulent Combustion Physics and Applications. - : Cambridge University Press. - 9781108671422 - 9781108497961 ; , s. 200-239
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Bokkapitel (refereegranskat)
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| 9. |
- Nilsson, T., et al.
(författare)
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Large Eddy Simulation of Ramjet to Scramjet Transition
- 2022
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Ingår i: 33rd Congress of the International Council of the Aeronautical Sciences, ICAS 2022. - 9781713871163 ; 6, s. 4513-4527
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Konferensbidrag (refereegranskat)abstract
- The dual-mode ramjet engine is one of the most promising propulsion systems for hypersonic flight because it can be operated in a wide range of flight Mach numbers. This engine type will be quite complicated to use in practice since it requires Ma<2 and therefore needs to be complemented by a turbojet engine for take-off, landing and low speed maneuvering. The dual mode ramjet engine will operate in a thermally choked ramjet mode for moderate speeds with 3
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| 10. |
- Nilsson, T., et al.
(författare)
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LES of H2-air jet combustion in high enthalpy supersonic crossflow
- 2021
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Ingår i: Physics of Fluids. - : AIP Publishing. - 1070-6631 .- 1089-7666. ; 33:3
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Tidskriftsartikel (refereegranskat)abstract
- Here, we report on large eddy simulation (LES) of supersonic flow, mixing, self-ignition, and combustion in a supersonic hydrogen jet in a crossflow configuration. The configuration has been experimentally investigated at Stanford and consists of a rectilinear channel with a ramp inlet in which a hydrogen jet discharges at a 90° angle to the high enthalpy supersonic crossflow. This configuration has been extensively studied by several research groups and constitutes a good validation case for model development and physics elucidation. The LES model used is based on an unstructured finite volume discretization of the filtered mass, momentum, species, and energy equations and an explicit flow solver. In this study, we investigate the effects of the jet-to-crossflow momentum ratio, the chemical reaction mechanism, and the combustion subgrid model by comparing predictions and by comparing with experimental data including OH* chemiluminescence images and jet penetration data. In general, good agreement is found but with some departures for the smallest reaction mechanisms and some of the LES combustion models. The LES results are also used to elucidate the flow, mixing, and combustion features of this configuration.
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