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Engström, Fredrik
Publications (7 of 7) Show all publications
Soltani Dehkharqani, A., Aidanpää, J.-O., Engström, F. & Cervantes, M. (2019). Fluid added polar inertia and damping for the torsional vibration of a Kaplan turbine model runner considering multiple perturbations. In: IOP Conference Series: Earth and Environmental Science. Paper presented at 29th IAHR Symposium on Hydraulic Machinery and Systems, 17-21 September 2018, Kyoto, Japan.. Institute of Physics (IOP), 240, Article ID 062007.
Open this publication in new window or tab >>Fluid added polar inertia and damping for the torsional vibration of a Kaplan turbine model runner considering multiple perturbations
2019 (English)In: IOP Conference Series: Earth and Environmental Science, Institute of Physics (IOP), 2019, Vol. 240, article id 062007Conference paper, Published paper (Refereed)
Abstract [en]

A water turbine runner is exposed to several perturbation sources with differentfrequencies, phases, and amplitudes both at the design and off-design operations. Rotor-statorinteraction, cavitation, rotating vortex rope, and blade trailing edge vortices are examples of suchperturbations which can disturb the runner. The rotor dynamic coefficients require beingdetermined to perform a reliable dynamic analysis. Fluid added inertia, damping, and stiffnesshave previously been investigated for individual perturbation frequencies for the torsionalvibration of a Kaplan turbine model runner. However, a number of perturbation sources mostlytake place simultaneously and alter the dynamics of the runner. Soltani et al. [1] have evaluatedthe torsional added parameters for a Kaplan turbine runner using numerical simulationsconsidering single perturbation frequency. In the present work, the fluid added parameters areassessed in the presence of multiple perturbation sources. A similar methodology is used. Asingle-degree-of-freedom (SDOF) model for the dynamic model and unsteady ReynoldsaveragedNavier–Stokes approach for the flow simulations are assumed. Perturbations withdifferent frequencies are applied to the rotational speed of the runner to determine the fluid addedparameters for the torsional vibration. A number of previously investigated frequencies arechosen and their combinations are investigated. In addition, two different phase shifts areconsidered between the applied perturbations to study the effect of phase. Two more test caseswith higher perturbation amplitude are also conducted to investigate its influence on the fluidadded inertia and damping. The results are compared with the previous study and the interactionof multiple perturbations on the added parameters is investigated.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2019
National Category
Mechanical Engineering Fluid Mechanics and Acoustics Other Mechanical Engineering
Research subject
Fluid Mechanics; Computer Aided Design
Identifiers
urn:nbn:se:ltu:diva-72503 (URN)10.1088/1755-1315/240/6/062007 (DOI)2-s2.0-85063961671 (Scopus ID)
Conference
29th IAHR Symposium on Hydraulic Machinery and Systems, 17-21 September 2018, Kyoto, Japan.
Available from: 2019-01-09 Created: 2019-01-09 Last updated: 2019-06-26Bibliographically approved
Soltani Dehkharqani, A., Aidanpää, J.-O., Engström, F. & Cervantes, M. (2018). A Review of Available Methods for the Assessment of Fluid Added Mass, Damping, and Stiffness With an Emphasis on Hydraulic Turbines. Applied Mechanics Review, 70(5), Article ID 050801.
Open this publication in new window or tab >>A Review of Available Methods for the Assessment of Fluid Added Mass, Damping, and Stiffness With an Emphasis on Hydraulic Turbines
2018 (English)In: Applied Mechanics Review, ISSN 0003-6900, E-ISSN 1088-8535, Vol. 70, no 5, article id 050801Article in journal (Refereed) Published
Abstract [en]

Fluid added mass, damping, and stiffness are highly relevant parameters to consider when evaluating the dynamic response of a submerged structure in a fluid. The prediction of these parameters for hydraulic turbines has been approached relatively recently. Complex fluid-structure analyses including three-dimensional flow and the need for experiments during operation are the main challenges for the numerical and experimental approaches, respectively. The main objective of this review is to address the impact of different parameters, for example, flow velocity, cavitation, nearby solid structure, and rotational speed on the fluid added mass and damping of Kaplan/Propeller and Francis turbine runners. The fluid added stiffness is also discussed in the last section of the paper. Although studies related to hydraulic turbines are the main objective of this paper, the literature on hydrofoils is also taken into consideration to provide valuable information on topics such as individual runner blades. In this literature survey, the analytical, numerical, and experimental approaches used to determine fluid added parameters are discussed, and the pros and the cons of each method are addressed.

Place, publisher, year, edition, pages
ASME Press, 2018
Keywords
fluid added mass, fluid added damping, fluid added stiffness, Francis turbine, Kaplan turbine, hydrofoils
National Category
Fluid Mechanics and Acoustics Other Mechanical Engineering
Research subject
Fluid Mechanics; Computer Aided Design
Identifiers
urn:nbn:se:ltu:diva-72502 (URN)10.1115/1.4042279 (DOI)000458511300001 ()2-s2.0-85059957623 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-01-29 (svasva)

Available from: 2019-01-09 Created: 2019-01-09 Last updated: 2019-08-26Bibliographically approved
Cervantes, M. & Engström, F. (2008). Pulsating turbulent flow in a straight asymmetric diffuser (ed.). Journal of Hydraulic Research, 46(Suppl. 1), 112-128
Open this publication in new window or tab >>Pulsating turbulent flow in a straight asymmetric diffuser
2008 (English)In: Journal of Hydraulic Research, ISSN 0022-1686, E-ISSN 1814-2079, Vol. 46, no Suppl. 1, p. 112-128Article in journal (Refereed) Published
Abstract [en]

Pulsating turbulent flow is studied for four regimes: steady, quasi-steady, relaxation, and quasi-laminar in a rectangular straight asymmetric diffuser, a generic model of the diffuser found at the end of most Kaplan and Francis type hydropower turbines. The flow entering the diffuser is a developing duct flow at Reynolds number 20 000, based on mean streamwise velocity and hydraulic diameter. The time averaged velocity and turbulent quantities are not affected by the forced oscillation. The regimes prevail in the diffuser, but are shifted due to the decreasing friction velocity. The oscillating quantities are affected by the adverse pressure gradient in the same way as the time averaged quantities, but with a decreasing effect for higher forcing frequencies. The amplitude of the oscillating wall shear stress is found to be signicantly lower than the Stokes solution in the quasi-laminar regime. The regime is confirmed by the behaviour of several other quantities. The pressure recovery is found to be 30 % higher in the relaxation regime than in the other regimes. Results are compared with experiments in channels and turbulent boundary layers, with and without an adverse pressure gradient, and with large-eddy simulations.

National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-12176 (URN)b43c9260-114f-11dd-ada4-000ea68e967b (Local ID)b43c9260-114f-11dd-ada4-000ea68e967b (Archive number)b43c9260-114f-11dd-ada4-000ea68e967b (OAI)
Note

Validerad; 2008; 20080423 (cervante)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2019-06-26Bibliographically approved
Cervantes, M. & Engström, F. (2005). Eddy viscosity turbulence models and steady draft tube simulations (ed.). In: (Ed.), Turbine-99 III: Proceedings of the third IAHR/ERCOFTAC workshop on draft tube flow. Paper presented at IAHR/ERCOFTAC workshop on draft tube flow : 08/12/2005 - 09/12/2005 (pp. 37-44). Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Eddy viscosity turbulence models and steady draft tube simulations
2005 (English)In: Turbine-99 III: Proceedings of the third IAHR/ERCOFTAC workshop on draft tube flow, Luleå: Luleå tekniska universitet, 2005, p. 37-44Conference paper, Published paper (Refereed)
Abstract [en]

Computations of the Turbine-99 benchmark have been performed for two dimensional steady inlet boundary conditions. Three different turbulence models were used: zero equation model, k-ε and shear stress model (SST). The results from the engineering quantities indicate small differences on the mean pressure recovery and the loss factor, while larger differences appear for the wall pressure recovery.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2005
Series
Research report / Luleå University of Technology, ISSN 1402-1528 ; 2005:20
National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-32695 (URN)743927e0-a239-11db-8975-000ea68e967b (Local ID)743927e0-a239-11db-8975-000ea68e967b (Archive number)743927e0-a239-11db-8975-000ea68e967b (OAI)
Conference
IAHR/ERCOFTAC workshop on draft tube flow : 08/12/2005 - 09/12/2005
Note

Godkänd; 2005; 20070112 (ysko)

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2019-06-26Bibliographically approved
Cervantes, M., Engström, F. & Gustavsson, H. (Eds.). (2005). Turbine-99 III: Proceedings of the third IAHR/ERCOFTAC workshop on draft tube flow. Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Turbine-99 III: Proceedings of the third IAHR/ERCOFTAC workshop on draft tube flow
2005 (English)Collection (editor) (Other academic)
Abstract [en]

The third IAHR/ERCOFTAC workshop on draft tube flows, Turbine-99 III, is based on the experience gained during the first two workshops and the development of the computational capacities. It is expected to be a step towards better understanding of draft tube flow simulation capabilities. Three cases based on the Turbine-99 benchmark were proposed to the participants: steady calculation, unsteady calculation, optimization of the draft tube performance. More than 30 simulations have been performed by the participants with several turbulence models, near wall treatment, grids and boundary conditions. The complexity of the turbulence models ranges from zero equation model to large eddy simulations. The contribution of the different participants, the protocol of their simulations and a comprehensive comparison of experimental data with the simulations are included in the present document.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2005. p. 193
Series
Research report / Luleå University of Technology, ISSN 1402-1528 ; 2005:20
National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-21594 (URN)3b975190-a244-11db-8975-000ea68e967b (Local ID)3b975190-a244-11db-8975-000ea68e967b (Archive number)3b975190-a244-11db-8975-000ea68e967b (OAI)
Note

Godkänd; 2005; Bibliografisk uppgift: IAHR/ERCOFTAC workshop on draft tube flow 3 Porjus, Sweden 08.12.2005 - 09.12.2005; 20070112 (ysko)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2019-06-26Bibliographically approved
Cervantes, M. & Engström, F. (2004). Factorial design applied to CFD (ed.). Journal of Fluids Engineering - Trancactions of The ASME, 126(5), 791-798
Open this publication in new window or tab >>Factorial design applied to CFD
2004 (English)In: Journal of Fluids Engineering - Trancactions of The ASME, ISSN 0098-2202, E-ISSN 1528-901X, Vol. 126, no 5, p. 791-798Article in journal (Refereed) Published
Abstract [en]

Factorial design, a statistical method widely used for experiments, and its application to CFD are discussed. The aim is to propose a systematic, objective, and quantitative method for engineers to design a set of simulations in order to evaluate main and joint effects of input parameters on the numerical solution. The input parameters may be experimental uncertainty on boundary conditions, unknown boundary conditions, grid, differencing schemes, and turbulence models. The complex flow of the Turbine-99 test case, a hydropower draft tube flow, is used to illustrate the method, where four factors are chosen to perform a 24 factorial design. The radial velocity at the inlet (not measured) is shown to have an important influence on the pressure recovery (7%) and the energy loss factor (49%).

National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-12710 (URN)10.1115/1.1792277 (DOI)000225805500011 ()2-s2.0-11144282525 (Scopus ID)bdfbf190-a555-11db-8975-000ea68e967b (Local ID)bdfbf190-a555-11db-8975-000ea68e967b (Archive number)bdfbf190-a555-11db-8975-000ea68e967b (OAI)
Note

Validerad; 2004; 20070116 (ysko)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2019-06-26Bibliographically approved
Andersson, U., Engström, F., Gustavsson, H. & Karlsson, R. (2004). The Turbine-99 workshops - conclusions and recommendations (ed.). In: (Ed.), 22nd IAHR Symposium on Hydraulic Machinery and Systems, Stockholm, Sweden, June 29 - July 2, 2004: . Paper presented at IAHR Symposium on Hydraulic Machinery and Systems : 29/06/2004 - 02/07/2004. Stockholm: IAHR
Open this publication in new window or tab >>The Turbine-99 workshops - conclusions and recommendations
2004 (English)In: 22nd IAHR Symposium on Hydraulic Machinery and Systems, Stockholm, Sweden, June 29 - July 2, 2004, Stockholm: IAHR , 2004Conference paper, Published paper (Other academic)
Place, publisher, year, edition, pages
Stockholm: IAHR, 2004
National Category
Metallurgy and Metallic Materials Fluid Mechanics and Acoustics
Research subject
Process Metallurgy; Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-30580 (URN)46f69e60-629c-11dc-ac97-000ea68e967b (Local ID)46f69e60-629c-11dc-ac97-000ea68e967b (Archive number)46f69e60-629c-11dc-ac97-000ea68e967b (OAI)
Conference
IAHR Symposium on Hydraulic Machinery and Systems : 29/06/2004 - 02/07/2004
Note

Godkänd; 2004; Bibliografisk uppgift: CD-ROM; 20070914 (ysko)

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2019-06-26Bibliographically approved
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