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Publications (10 of 24) Show all publications
Andersson, L. R., Larsson, S., Hellström, J. G., Andreasson, P., Andersson, A. G. & Lundström, S. (2018). Characterization of Flow Structures Induced by Highly Rough Surface Using Particle Image Velocimetry, Proper Orthogonal Decomposition and Velocity Correlations. Engineering, 10, 399-416
Open this publication in new window or tab >>Characterization of Flow Structures Induced by Highly Rough Surface Using Particle Image Velocimetry, Proper Orthogonal Decomposition and Velocity Correlations
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2018 (English)In: Engineering, ISSN 1947-3931, Vol. 10, p. 399-416Article in journal (Refereed) Published
Abstract [en]

High Reynolds number flow inside a channel of rectangular cross section is examined using Particle Image Velocimetry. One wall of the channel has been replaced with a surface of a roughness representative to that of real hydropower tunnels, i.e. a random terrain with roughness dimensions typically in the range of ≈10% - 20% of the channels hydraulic radius. The rest of the channel walls can be considered smooth. The rough surface was captured from an existing blasted rock tunnel using high resolution laser scanning and scaled to 1:10. For quantification of the size of the largest flow structures, integral length scales are derived from the auto-correlation functions of the temporally averaged velocity. Additionally, Proper Orthogonal Decomposition (POD) and higher-order statistics are applied to the instantaneous snapshots of the velocity fluctuations. The results show a high spatial heterogeneity of the velocity and other flow characteristics in vicinity of the rough surface, putting outer similarity treatment into jeopardy. Roughness effects are not confined to the vicinity of the rough surface but can be seen in the outer flow throughout the channel, indicating a different behavior than postulated by Townsend’s similarity hypothesis. The effects on the flow structures vary depending on the shape and size of the roughness elements leading to a high spatial dependence of the flow above the rough surface. Hence, any spatial averaging, e.g. assuming a characteristic sand grain roughness factor, for determining local flow parameters becomes less applicable in this case.

Place, publisher, year, edition, pages
Scientific Research Publishing, 2018
Keywords
CFD, Validation, Hydraulic Roughness, PIV, Hydropower
National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-71097 (URN)10.4236/eng.2018.107028 (DOI)
Note

Validerad;2020;Nivå 1;2020-01-07 (marisr)

Available from: 2018-10-04 Created: 2018-10-04 Last updated: 2020-01-07Bibliographically approved
Teng, Z., Larsson, S., Lundström, S. & Marjavaara, B. D. (2018). The Effect of Reynolds Number on Jet in Asymmetric Co-Flows: A CFD Study. International Journal of Chemical Engineering, Article ID 1572576.
Open this publication in new window or tab >>The Effect of Reynolds Number on Jet in Asymmetric Co-Flows: A CFD Study
2018 (English)In: International Journal of Chemical Engineering, ISSN 1687-806X, E-ISSN 1687-8078, article id 1572576Article in journal (Refereed) Published
Abstract [en]

In rotary kilns in grate-kiln systems for iron ore pelletizing, a long and stable jet flame is needed to ensure a high quality of the pellets. The primary jet issuing from the nozzle interacts with two asymmetric co-flows creating a very complex flow. In order to better understand and eventually model this flow with quality and trust, simplified cases need to be studied. In this work, a simplified and virtual model is built based on a down-scaled kiln model established in a previous experimental work. The aim is to numerically study the jet development as a function of position and Reynolds number (Re). The numerical simulations are carried out with the standard k-ε model, and quite accurate velocity profiles are obtained while the centerline decays and spreading of the passive scalars are over predicted. The model is capable of predicting a Re dependency of the jet development. With increasing Re, the jet is longer while it generally decays and spreads faster resulting from the stronger shear between the jet and co-flows and the stronger entrainment from the recirculation zone. This recirculation found in the simulations restrain the momentum spreading in the spanwise direction, leading to a slower velocity spreading with higher Re. For further validation and understanding, more measurements in the shear layer and simulations with more advanced turbulence models are necessary

Place, publisher, year, edition, pages
Hindawi Publishing Corporation, 2018
National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-71461 (URN)10.1155/2018/1572576 (DOI)000449197900001 ()2-s2.0-85056223095 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-11-06 (johcin) 

Available from: 2018-11-06 Created: 2018-11-06 Last updated: 2018-12-05Bibliographically approved
Larsson, S., Lundström, S. & Lycksam, H. (2018). Tomographic PIV of flow through ordered thin porous media. Experiments in Fluids, 59(6), Article ID 96.
Open this publication in new window or tab >>Tomographic PIV of flow through ordered thin porous media
2018 (English)In: Experiments in Fluids, ISSN 0723-4864, E-ISSN 1432-1114, Vol. 59, no 6, article id 96Article in journal (Refereed) Published
Abstract [en]

Pressure-driven flow in a model of a thin porous medium is investigated using tomographic particle image velocimetry. The solid parts of the porous medium have the shape of vertical cylinders placed on equal interspatial distance from each other. The array of cylinders is confined between two parallel plates, meaning that the permeability is a function of the diameter and height of the cylinders, as well as their interspatial distance. Refractive index matching is applied to enable measurements without optical distortion and a dummy cell is used for the calibration of the measurements. The results reveal that the averaged flow field changes substantially as Reynolds number increases, and that the wakes formed downstream the cylinders contain complex, three-dimensional vortex structures hard to visualize with only planar measurements. An interesting observation is that the time-averaged velocity maximum changes position as Reynolds number increases. For low Reynolds number flow, the maximum is in the middle of the channel, while, for the higher Reynolds numbers investigated, two maxima appear closer to each bounding lower and upper wall.

Place, publisher, year, edition, pages
Springer, 2018
National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-68773 (URN)10.1007/s00348-018-2548-6 (DOI)000459501500001 ()2-s2.0-85047216388 (Scopus ID)
Note

Validerad;2018;Nivå 1;20180525 (marisr)

Available from: 2018-05-17 Created: 2018-05-17 Last updated: 2019-03-14Bibliographically approved
Teng, Z., Johansson, S., Larsson, S., Lundström, S. & Marjavaara, D. (2016). CFD Simulation of Jet Mixing with Asymmetric Co-flows in a Down-scaled Rotary Kiln Model. In: Proceedings of the ASME 2016 International Mechanical Engineering Congress and Exposition: . Paper presented at ASME 2016 International Mechanical Engineering Congress and Exposition (IMECE 2016), Phoenix, Arizona, USA, November 11–17, 2016. ASME Press, 7, Article ID IMECE2016-65637.
Open this publication in new window or tab >>CFD Simulation of Jet Mixing with Asymmetric Co-flows in a Down-scaled Rotary Kiln Model
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2016 (English)In: Proceedings of the ASME 2016 International Mechanical Engineering Congress and Exposition, ASME Press, 2016, Vol. 7, article id IMECE2016-65637Conference paper, Published paper (Refereed)
Abstract [en]

Rotary kilns used in the iron pellet production in the grate-kiln pelletizing process normally have two asymmetric secondary air channels. The primary jet is ejected from a burner located in the middle of a back plate. As a consequence of the high flow rates and irregular-shaped secondary air channels, the aerodynamics in the kiln is strongly connected to the combustion and sintering performance. In this work a Computational Fluid Dynamics study is performed on a downscaled, simplified kiln model established in earlier numerical and experimental work. Comparisons are made with the experiment and among three turbulence models, the standard k-ε model, a k-ε model modified for turbulent axisymmetric round jets and Speziale-Sarkar-Garski Reynolds Stress Model (SSG-RSM hereafter). Recirculation regions with negative axial velocity are found at the upper side of the kiln and behind the back plate. Results from the standard k-ε model have the best fit to the experimental data regarding the centerline decay and the jet spreading of the velocity. The spreading rate of the scalar concentration calculated from the results with the modified k-ε model and the SSG-RSM fit better with the experiment, but they both underestimate the centerline decay and the spreading of the velocity. The modified k-ε model yields a more physical and realistic flow field compared to the standard k-ε model, and the results are close to those obtained with the SSG-RSM. Unlike the isotropic development of the jet predicted with the standard k-ε model, the modified k-ε model and the SSG-RSM show different development of the jet in the horizontal and vertical directions.

Place, publisher, year, edition, pages
ASME Press, 2016
National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-60693 (URN)10.1115/IMECE2016-65637 (DOI)000400877800062 ()2-s2.0-85021639527 (Scopus ID)978-0-7918-5061-9 (ISBN)
Conference
ASME 2016 International Mechanical Engineering Congress and Exposition (IMECE 2016), Phoenix, Arizona, USA, November 11–17, 2016
Projects
Faste Laboratory
Funder
VINNOVA, 197426
Available from: 2016-11-25 Created: 2016-11-25 Last updated: 2017-11-29Bibliographically approved
Teng, Z., Larsson, S., Lundström, S. & Marjavaara, D. (2016). Computational Fluid Dynamics Modelling of Flow Field in a Simplified, Down-scaled Rotary Kiln Model. In: : . Paper presented at 11th European Fluid Mechanics Conference, Seville Spain, 12-16 Sept 2016.
Open this publication in new window or tab >>Computational Fluid Dynamics Modelling of Flow Field in a Simplified, Down-scaled Rotary Kiln Model
2016 (English)Conference paper, Oral presentation with published abstract (Other academic)
Keywords
Rotary kiln, CFD, Jet, Turbulence
National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-60691 (URN)
Conference
11th European Fluid Mechanics Conference, Seville Spain, 12-16 Sept 2016
Available from: 2016-11-25 Created: 2016-11-25 Last updated: 2017-11-29Bibliographically approved
Andersson, R., Larsson, S., Hellström, G., Andreasson, P. & Andersson, A. (2016). Experimental Study of Head Loss over Laser Scanned Rock Tunnel (ed.). In: (Ed.), Experimental Study of Head Loss over Laser Scanned Rock Tunnel: Hydraulic Structures and Water System Management, ISHS 2016, Portland, United States, 27 - 30 June 2016. Paper presented at International Symposium on Hydraulic Structures : 27/06/2016 - 30/06/2016 (pp. 22-29). Portland: Utah State University
Open this publication in new window or tab >>Experimental Study of Head Loss over Laser Scanned Rock Tunnel
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2016 (English)In: Experimental Study of Head Loss over Laser Scanned Rock Tunnel: Hydraulic Structures and Water System Management, ISHS 2016, Portland, United States, 27 - 30 June 2016, Portland: Utah State University , 2016, p. 22-29Conference paper, Published paper (Refereed)
Abstract [en]

Flow in hydropower tunnels is characterized by a high Reynolds number and often very rough rock walls. Due to the roughness of the walls, the flow in the tunnel is highly disturbed, resulting in large fluctuations of velocity and pressure in both time and space. Erosion problems and even partial collapse of tunnel walls are in some cases believed to be caused by hydraulic jacking from large flow induced pressure fluctuations. The objective of this work is to investigate the effects of the rough walls on the pressure variations in time and space over the rock surfaces. Pressure measurement experiments were performed in a 10 m long Plexiglas tunnel where one of the smooth walls was replaced with a rough surface. The rough surface was created from a down-scaled (1:10) laser scanned wall of a hydraulic tunnel. The differential pressure was measured at the smooth surface between points placed at the start and end of the first four 2 m sections of the channel. 10 gauge pressure sensors where flush mounted on the rough surface; these sensors measure the magnitude and the fluctuations of the pressure on the rough surface. The measurements showed significant spatial variation of the pressure on the surface. For example, sensors placed on protruding roughness elements showed low gauge pressure but high fluctuations. The differential pressure indicated a head loss through the tunnel that was almost four times higher than a theoretical smooth channel.

Place, publisher, year, edition, pages
Portland: Utah State University, 2016
National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-40310 (URN)10.15142/T360628160853 (DOI)2-s2.0-84988981565 (Scopus ID)f63f31d3-d2db-4351-8149-87a65d10ced0 (Local ID)978-1-884575-75-4 (ISBN)f63f31d3-d2db-4351-8149-87a65d10ced0 (Archive number)f63f31d3-d2db-4351-8149-87a65d10ced0 (OAI)
Conference
International Symposium on Hydraulic Structures : 27/06/2016 - 30/06/2016
Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2018-10-04Bibliographically approved
Larsson, S., Marjavaara, D. & Lundström, S. (2016). Simulation of the flow field in an iron ore pelletizing kiln (ed.). Minerals & metallurgical processing, 33(3), 144-148
Open this publication in new window or tab >>Simulation of the flow field in an iron ore pelletizing kiln
2016 (English)In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 33, no 3, p. 144-148Article in journal (Refereed) Published
Abstract [en]

The flow field in a rotary kiln, used in an iron ore pelletizing process, was investigated using a three-dimensional computational fluid dynamics model. The model is isothermal, downscaled and simplified. The objective was to examine the possibility of capturing the unsteady motion of the flame seen in the real kiln. The results from the simulations were compared with recorded images of the real process. The results demonstrate the possibility of quickly getting an overview of the flow field in the kiln. The main, unsteady behavior of the flame was captured. The model may be used as a tool in the ongoing work of improving and optimizing the pelletizing process.

National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-3386 (URN)10.19150/mmp.6751 (DOI)000381242700006 ()2-s2.0-85009223198 (Scopus ID)1354b68f-677b-4b6e-ac68-537841efb43e (Local ID)1354b68f-677b-4b6e-ac68-537841efb43e (Archive number)1354b68f-677b-4b6e-ac68-537841efb43e (OAI)
Note

Validerad; 2016; Nivå 2; 20160511 (stlu)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Sas, D., Larsson, S., Dagman, A. & Karlberg, M. (2015). Aggregation of solutions for Functional Product life cycle: review of results from the Faste Laboratory (ed.). Paper presented at International Through-Life Engineering Services Conference : 03/11/2015 - 04/11/2015. Procedia CIRP, 38, 216-221
Open this publication in new window or tab >>Aggregation of solutions for Functional Product life cycle: review of results from the Faste Laboratory
2015 (English)In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 38, p. 216-221Article in journal (Refereed) Published
Abstract [en]

Functional Product (FP) can be viewed as a business concept which is aimed at offering a function or performance to customer on an agreed upon level of availability and cost as well as at providing incitements towards a sustainable growth. The development and operation of FP is a multidisciplinary and complex process. To support such process often advanced and creative solutions are required. Based on analysis of research conducted in the Faste Laboratory, this paper aggregates FP solutions consisting of existing methods, tools and models. Further, utilisation of FP solutions is discussed from the FP life cycle perspective.

National Category
Other Mechanical Engineering Fluid Mechanics and Acoustics
Research subject
Computer Aided Design; Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-34524 (URN)10.1016/j.procir.2015.08.033 (DOI)000381110000037 ()2-s2.0-84964048524 (Scopus ID)8bf37610-908a-4160-af23-d568e79fb439 (Local ID)8bf37610-908a-4160-af23-d568e79fb439 (Archive number)8bf37610-908a-4160-af23-d568e79fb439 (OAI)
Conference
International Through-Life Engineering Services Conference : 03/11/2015 - 04/11/2015
Projects
Fastelaboratoriet - VINNEXC
Note

Validerad; 2015; Nivå 1; 20150916 (darpla)

; Konferensartikel i tidskriftAvailable from: 2016-09-30 Created: 2016-09-30 Last updated: 2019-03-18Bibliographically approved
Larsson, S., Lundström, T. S. & Marjavaara, D. (2015). Calculation of Kiln Aerodynamics with two RANS turbulence models and by DDES (ed.). Paper presented at . Flow Turbulence and Combustion, 94(4), 859-878
Open this publication in new window or tab >>Calculation of Kiln Aerodynamics with two RANS turbulence models and by DDES
2015 (English)In: Flow Turbulence and Combustion, ISSN 1386-6184, E-ISSN 1573-1987, Vol. 94, no 4, p. 859-878Article in journal (Refereed) Published
Abstract [en]

Rotary kilns are large, cylindrical, rotating ovens with a burner in one end that are used in various industrial processes to heat up materials to high temperatures. The kiln burners are characterized by long diffusion flames where the combustion process is largely controlled by the turbulent diffusion mixing between the burner fuel jet and the surrounding combustion air. The combustion air flow patterns have a significant effect on the mixing and hence the combustion efficiency, motivating a systematic study of the kiln aerodynamics. The objective of this work is to compare turbulence models when modeling the kiln aerodynamics of an iron ore pelletizing rotary kiln. Simulations of the non-reacting isothermal flow using three different ω-based turbulence models are performed on a simplified, down-scaled model of the kiln. Some of the results are validated against particle image velocimetry (PIV) experiments. The turbulence models used are the two-equation shear stress transport (SST) model, the Reynolds stress baseline (RSM-BSL) model and the delayed detached eddy simulation (DDES) turbulence model based on the SST formulation. It is found that the turbulence models produce quite different results yielding various predictions of the flow field. The SST model fails to capture the unsteady behavior of the flow field and the DDES model performs poorly on the grid applied. The Reynolds stress model agrees best when compared with the experimental data and provides a good trade-off between details captured and computational effort.

National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-14244 (URN)10.1007/s10494-015-9602-8 (DOI)000354283400007 ()2-s2.0-84937929312 (Scopus ID)d986d7bc-acac-464a-8fe1-158b018c2730 (Local ID)d986d7bc-acac-464a-8fe1-158b018c2730 (Archive number)d986d7bc-acac-464a-8fe1-158b018c2730 (OAI)
Note
Validerad; 2015; Nivå 2; 20150127 (stlu)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Larsson, S., Johansson, S., Lundström, T. S. & Marjavaara, D. (2015). PIV/PLIF experiments of jet mixing in a model of a rotary kiln (ed.). Paper presented at . Experiments in Fluids, 56(5), Article ID 111.
Open this publication in new window or tab >>PIV/PLIF experiments of jet mixing in a model of a rotary kiln
2015 (English)In: Experiments in Fluids, ISSN 0723-4864, E-ISSN 1432-1114, Vol. 56, no 5, article id 111Article in journal (Refereed) Published
National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-7000 (URN)10.1007/s00348-015-1984-9 (DOI)000354473900025 ()2-s2.0-84929224074 (Scopus ID)5559a837-9fc1-4b4e-bf10-dad310266d5b (Local ID)5559a837-9fc1-4b4e-bf10-dad310266d5b (Archive number)5559a837-9fc1-4b4e-bf10-dad310266d5b (OAI)
Note
Validerad; 2015; Nivå 2; 20150429 (stlu)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-4916-9566

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