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Aidanpää, Jan-OlovORCID iD iconorcid.org/0000-0001-6016-6342
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Publications (10 of 112) Show all publications
Rondon, D., Aidanpää, J.-O., Gustavsson, R., Lundin, U. & Jeppsson, P. (2023). Dynamic model for hydropower generators with floating rotor rim. Mechanical systems and signal processing, 183, Article ID 109645.
Open this publication in new window or tab >>Dynamic model for hydropower generators with floating rotor rim
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2023 (English)In: Mechanical systems and signal processing, ISSN 0888-3270, E-ISSN 1096-1216, Vol. 183, article id 109645Article in journal (Refereed) Published
Abstract [en]

For rotordynamic analysis of hydropower units, the generator is treated as a rotating rigid body. However, previous studies have confirmed that certain designs of generators are elastic, so the complex geometry of generators cannot be considered rigid. This work produced a model of hydropower generators with floating rotor rims, consisting of a rigid hub and a flexible rotor rim coupled with flexible connections. The model takes into account the influence of centrifugal and Coriolis effects, and the electromagnetic interaction between rotor and stator. The model also reproduces the dynamics of the generator with static and dynamic eccentricities. A generator prototype was employed to test the model, showing its different applications. Once validated by empirical data, this model could be used when designing generators.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Rotordynamics, Magnetic force, Generator model, Hydropower, Dynamic modeling, Curved beam
National Category
Applied Mechanics
Research subject
Machine Design
Identifiers
urn:nbn:se:ltu:diva-88899 (URN)10.1016/j.ymssp.2022.109645 (DOI)000877355300003 ()2-s2.0-85135882306 (Scopus ID)
Projects
Swedish Hydropower Centre - SVC
Funder
Swedish Energy AgencyLuleå University of TechnologyChalmers University of TechnologyUppsala UniversityLund University
Note

Validerad;2022;Nivå 2;2022-08-19 (hanlid);

Funder: Energiforsk, Svenska Kraftnät, KTH Royal Institute of Technology

Available from: 2022-01-24 Created: 2022-01-24 Last updated: 2023-09-05Bibliographically approved
Benti, G. B., Aidanpää, J.-O. & Gustavsson, R. (2023). Simplified transformation matrices of journal bearings in vertical application. Applications in Engineering Science, 15, Article ID 100147.
Open this publication in new window or tab >>Simplified transformation matrices of journal bearings in vertical application
2023 (English)In: Applications in Engineering Science, E-ISSN 2666-4968, Vol. 15, article id 100147Article in journal (Refereed) Published
Abstract [en]

Rotodynamic simulation of complex or/and large systems, for instance hydropower machines, may consist of models with many degrees of freedom and require multidisciplinary computations such as fluid-thermal-structure interactions or rotor-stator interactions due to electromagnetic forces. Simulating such systems is often computationally heavy and impractical, especially in the case of optimization or parametric study, where many iterations are required. This has, therefore, created a need for simplified dynamic models to improve computational efficiency without significantly affecting the accuracy of the simulation result. The purpose of this paper is to present simplified coordinate transformation matrices for journal bearings in vertical rotors, which require less computational effort. Matrix multiplications, which appear during coordinate transformation, were eliminated, and the bearing stiffness and damping matrices in the fixed reference frame were represented by local coefficients instead. The dynamic response of a vertical rotor with eight-shoe Tilting pad journal bearings was simulated using the proposed model for two operational conditions, i.e., when the rotor was spinning at constant and variable speeds. The results from the proposed model were compared to those from the original model and validated through experiments. The conclusion was that the presented simulation model is time efficient and can effectively be used in rotordynamic simulations and analyses.

Place, publisher, year, edition, pages
Elsevier Ltd, 2023
Keywords
Bearing coefficient, Coordinate transformation, Rotordynamics, Tilting pad journal bearing, Vertical rotor
National Category
Other Mechanical Engineering
Research subject
Machine Design
Identifiers
urn:nbn:se:ltu:diva-101362 (URN)10.1016/j.apples.2023.100147 (DOI)001076998400001 ()2-s2.0-85170036228 (Scopus ID)
Note

Validerad;2023;Nivå 2;2023-09-18 (joosat);

CC BY 4.0 License

Available from: 2023-09-18 Created: 2023-09-18 Last updated: 2024-03-07Bibliographically approved
Rondon, D., Aidanpää, J.-O. & Gustavsson, R. (2022). Dynamic Model for Hydropower Generators with Floating Rotor-Rim. In: Pär Jonsén; Lars-Göran Westerberg; Simon Larsson; Erik Olsson (Ed.), Svenska Mekanikdagar 2022: . Paper presented at Svenska Mekanikdagarna 2022, Luleå, Sweden, June 15-16, 2022. Luleå tekniska universitet
Open this publication in new window or tab >>Dynamic Model for Hydropower Generators with Floating Rotor-Rim
2022 (English)In: Svenska Mekanikdagar 2022 / [ed] Pär Jonsén; Lars-Göran Westerberg; Simon Larsson; Erik Olsson, Luleå tekniska universitet, 2022Conference paper, Oral presentation with published abstract (Refereed)
Place, publisher, year, edition, pages
Luleå tekniska universitet, 2022
National Category
Applied Mechanics
Research subject
Machine Design
Identifiers
urn:nbn:se:ltu:diva-95142 (URN)
Conference
Svenska Mekanikdagarna 2022, Luleå, Sweden, June 15-16, 2022
Available from: 2023-01-03 Created: 2023-01-03 Last updated: 2023-09-05Bibliographically approved
Rondon, D., Aidanpää, J.-O. & Gustavsson, R. (2022). Effect of unbalancing mass placement in hydropower generators with floating rotor rim. In: 31st IAHR Symposium on Hydraulic Machinery and Systems 26/06/2022 - 01/07/2022 Trondheim, Norway: . Paper presented at 31st Symposium on Hydraulic Machinery and Systems (IAHR 2022), Trondheim, Norway, June 26 - July 1, 2022. Institute of Physics Publishing (IOPP) (1), Article ID 012094.
Open this publication in new window or tab >>Effect of unbalancing mass placement in hydropower generators with floating rotor rim
2022 (English)In: 31st IAHR Symposium on Hydraulic Machinery and Systems 26/06/2022 - 01/07/2022 Trondheim, Norway, Institute of Physics Publishing (IOPP) , 2022, no 1, article id 012094Conference paper, Published paper (Refereed)
Abstract [en]

Dynamic models for hydropower generators treat the rotor part as a rigid body; however, many studies have shown the opposite. The electromagnetic force distribution of deformed rotors is uneven, creating Unbalance Magnetic Pull, causing high forces on generator components leading to a risk of fatigue, therefore shortening the life of machines. Unbalancing masses can worsen the asymmetries of the rotor, which would further increase the effect of the electromagnetic interactions. This paper evaluates the rotor response using different unbalancing masses at the rotor and at the poles to quantify their impact in displacements and exciting frequencies. The model employed in this paper is based on the equation of motion derived using Lagrange equations in both co-rotating and stationary frames of reference, considering the effects of Centrifugal loads, Coriolis, and magnetization of poles. Different unbalancing mass placements affect different variables; extra weights in the poles contribute predominantly to the deformation of the rim, while the unbalance in the shaft affects the position of the shaft; a combination of placements was also studied. The simulations were performed and compared with and without radial electromagnetic forces, showing how the presence of magnetized poles further deforms the shapes of the rotor.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2022
Series
IOP Conference Series: Earth and Environmental Science, ISSN 1755-1307, E-ISSN 1755-1315 ; 1079
National Category
Applied Mechanics
Research subject
Machine Design
Identifiers
urn:nbn:se:ltu:diva-94712 (URN)10.1088/1755-1315/1079/1/012094 (DOI)2-s2.0-85141802042 (Scopus ID)
Conference
31st Symposium on Hydraulic Machinery and Systems (IAHR 2022), Trondheim, Norway, June 26 - July 1, 2022
Projects
Swedish Hydropower Centre - SVC
Funder
Swedish Energy AgencySwedish National GridLuleå University of TechnologyKTH Royal Institute of TechnologyChalmers University of TechnologyUppsala UniversityLund University
Available from: 2022-12-21 Created: 2022-12-21 Last updated: 2023-09-05Bibliographically approved
Benti, G. B., Gustavsson, R. & Aidanpää, J.-O. (2022). Experimental Investigation on Dynamics of a Flexible Rotor. In: Pär Jonsén; Lars-Göran Westerberg; Simon Larsson; Erik Olsson (Ed.), Svenska Mekanikdagar 2022: . Paper presented at Svenska Mekanikdagarna 2022, Luleå, Sweden, June 15-16, 2022. Luleå tekniska universitet
Open this publication in new window or tab >>Experimental Investigation on Dynamics of a Flexible Rotor
2022 (English)In: Svenska Mekanikdagar 2022 / [ed] Pär Jonsén; Lars-Göran Westerberg; Simon Larsson; Erik Olsson, Luleå tekniska universitet, 2022Conference paper, Oral presentation with published abstract (Refereed)
Place, publisher, year, edition, pages
Luleå tekniska universitet, 2022
National Category
Applied Mechanics
Research subject
Machine Design
Identifiers
urn:nbn:se:ltu:diva-95071 (URN)
Conference
Svenska Mekanikdagarna 2022, Luleå, Sweden, June 15-16, 2022
Available from: 2022-12-29 Created: 2022-12-29 Last updated: 2023-09-05Bibliographically approved
Benti, G. B., Rondon, D., Gustavsson, R. & Aidanpää, J.-O. (2022). Numerical and experimental study on the dynamic bearing properties of a four-pad and eight-pad tilting pad journal bearings in a vertical rotor . Journal of energy resources technology, 144(1)
Open this publication in new window or tab >>Numerical and experimental study on the dynamic bearing properties of a four-pad and eight-pad tilting pad journal bearings in a vertical rotor 
2022 (English)In: Journal of energy resources technology, ISSN 0195-0738, E-ISSN 1528-8994, Vol. 144, no 1Article in journal (Refereed) Published
Abstract [en]

In this paper, the dynamics of tilting pad journal bearings with four and eight pads are studied and compared experimentally and numerically. The experiments are performed on a rigid vertical rotor supported by two identical bearings. Two sets of experiments are carried out under similar test setup. One set is performed on a rigid rotor with two four-pad bearings, while the other is on a rigid rotor with two eight-pad bearings. The dynamic properties of the two bearing types are compared with each other by studying the unbalance response of the system at different rotor speeds. Numerically, the test rig is modeled as a rigid rotor and the bearing coefficients are calculated based on Navier-Stokes equation. A nonlinear bearing model is developed and used in the steady state response simulation. The measured and simulated displacement and force orbits show similar patterns for both bearing types. Compared to the measurement, the simulated mean value and range (peak-to-peak amplitude) of the bearing force deviate with a maximum of 16 % and 38 %, respectively. It is concluded that, unlike the eight-pad TPJB, the four-pad TPJB excite the system at the third and fifth-order frequencies, which are due to the number of pads, and the amplitudes of these frequencies increase with the rotor speed. 

Place, publisher, year, edition, pages
American Society of Mechanical Engineers (ASME), 2022
Keywords
Bearing Stiffness, Damping Coefficient, Tilting Pad Journal Bearing, Vertical Rotor
National Category
Applied Mechanics
Research subject
Machine Design
Identifiers
urn:nbn:se:ltu:diva-86610 (URN)10.1115/1.4052032 (DOI)000720985000020 ()2-s2.0-85137204906 (Scopus ID)
Note

Validerad;2021;Nivå 2;2021-09-01 (johcin)

Available from: 2021-08-16 Created: 2021-08-16 Last updated: 2024-03-07Bibliographically approved
Rondon, D., Benti, G. B., Aidanpää, J.-O. & Gustavsson, R. (2022). Rotordynamic Characterization of Tilting-Pad Bearings With Eight Pads in Vertical Rotors . Journal of energy resources technology, 144(1), Article ID 010902.
Open this publication in new window or tab >>Rotordynamic Characterization of Tilting-Pad Bearings With Eight Pads in Vertical Rotors 
2022 (English)In: Journal of energy resources technology, ISSN 0195-0738, E-ISSN 1528-8994, Vol. 144, no 1, article id 010902Article in journal (Refereed) Published
Abstract [en]

It has been documented that stiffness and damping for a four-pad bearing are dependent not only on the magnitude of the load but also on the position of the rotor in the bearing. However, eight-pad bearings are not commonly employed on horizontal turbines, and the presence of several pads in the bearing will decisively affect the dynamics of the system. This paper evaluates the stiffness and damping coefficients of tilting-pad bearings with eight pads and explores the main frequencies acting on the forced response of a vertical rotor. The bearing properties were modeled as a function of eccentricity and position in the stationary coordinate system by Navier–Stokes equations whose results are taken from commercial software. The simulated unbalanced response is compared to experimental results; the changing position of the shaft produces a periodic stiffness and damping, which is dependent on the number of pads. Cross-coupled coefficients influence is discussed, showing that their absence makes an accurate model for the mean values. The results indicate that simulation of vertical rotors with eight-pad bearings can be simplified which allow more effective simulations and dynamic analysis. 

Place, publisher, year, edition, pages
American Society of Mechanical Engineers (ASME), 2022
Keywords
tilting-pad bearing, vertical rotor
National Category
Applied Mechanics
Research subject
Machine Design
Identifiers
urn:nbn:se:ltu:diva-86562 (URN)10.1115/1.4051803 (DOI)000720985000005 ()2-s2.0-85121689564 (Scopus ID)
Funder
Swedish Energy AgencyLuleå University of Technology
Note

Validerad;2022;Nivå 2;2022-01-01 (johcin)

Available from: 2021-08-12 Created: 2021-08-12 Last updated: 2024-03-07Bibliographically approved
Benti, G. B., Gustavsson, R. & Aidanpää, J.-O. (2022). Speed-Dependent Bearing Models for Dynamic Simulations of Vertical Rotors. Machines, 10(7), Article ID 556.
Open this publication in new window or tab >>Speed-Dependent Bearing Models for Dynamic Simulations of Vertical Rotors
2022 (English)In: Machines, E-ISSN 2075-1702, Vol. 10, no 7, article id 556Article in journal (Refereed) Published
Abstract [en]

Many dynamic simulations of a rotor with a journal bearing employ non-linear fluid-film lubrication models and calculate the bearing coefficients at each time step. However, calculating such a simulation is tedious and computationally expensive. This paper presents a simplified dynamic simulation model of a vertical rotor with tilting pad journal bearings under constant and variable (transient) rotor spin speed. The dynamics of a four-shoes tilting pad journal bearing are predefined using polynomial equations prior to the unbalance response simulations of the rotor-bearing system. The Navier–Stokes lubrication model is solved numerically, with the bearing coefficients calculated for six different rotor speeds and nine different eccentricity amplitudes. Using a MATLAB inbuilt function (poly53), the stiffness and damping coefficients are fitted by a two-dimensional polynomial regression and the model is qualitatively evaluated for goodness-of-fit. The percentage relative error (RMSE%) is less than 10%, and the adjusted R-square (R2adj) is greater than 0.99. Prior to the unbalance response simulations, the bearing parameters are defined as a function of rotor speed and journal location. The simulation models are validated with an experiment based on the displacements of the rotor and the forces acting on the bearings. Similar patterns have been observed for both simulated and measured orbits and forces. The resultant response amplitudes increase with the rotor speed and unbalanced magnitude. Both simulation and experimental results follow a similar trend, and the amplitudes agree with slight deviations. The frequency content of the responses from the simulations is similar to those from the experiments. Amplitude peaks, which are associated with the unbalance force (1 × Ω) and the number of pads (3 × Ω and 5 × Ω), appeared in the responses from both simulations and experiments. Furthermore, the suggested simulation model is found to be at least three times faster than a classical simulation procedure that used FEM to solve the Reynolds equation at each time step.

Place, publisher, year, edition, pages
MDPI, 2022
Keywords
vertical rotor, rotor dynamics, transient, tilting pad journal bearing, bearing coefficient
National Category
Production Engineering, Human Work Science and Ergonomics
Research subject
Machine Design
Identifiers
urn:nbn:se:ltu:diva-92529 (URN)10.3390/machines10070556 (DOI)000832295500001 ()2-s2.0-85137216329 (Scopus ID)
Projects
Swedish Hydropower Centre-SVC
Funder
Swedish Energy AgencyLuleå University of TechnologyChalmers University of TechnologyUppsala UniversityLund University
Note

Validerad;2022;Nivå 2;2022-08-18 (hanlid);

Funder: Energiforsk, Svenska Kraftnät, KTH Royal Institute of Technology

Available from: 2022-08-18 Created: 2022-08-18 Last updated: 2023-09-05Bibliographically approved
Soltani Dehkharqani, A., Engström, F., Aidanpää, J.-O. & Cervantes, M. (2020). An Indirect Measurement Methodology to Identify Load Fluctuations on Axial Turbine Runner Blades. Sensors, 20(24), Article ID 7220.
Open this publication in new window or tab >>An Indirect Measurement Methodology to Identify Load Fluctuations on Axial Turbine Runner Blades
2020 (English)In: Sensors, E-ISSN 1424-8220, Vol. 20, no 24, article id 7220Article in journal (Refereed) Published
Abstract [en]

Smooth integration of intermittent energy sources, such as solar and wind power, into the electrical grid induces new operating conditions of the hydraulic turbine by increasing the off-design operations, start/stops, and load variations. Therefore, hydraulic turbines are subject to unstable flow conditions and unfavorable load fluctuations. Predicting load fluctuations on the runner using indirect measurements can allow for optimized operations of the turbine units, increase turbine refurbishment time intervals, and avoid structural failures in extreme cases. This paper investigates an experimental methodology to assess and predict the flow condition and load fluctuations on a Kaplan turbine runner at several steady-state operations by performing measurements on the shaft in the rotating and stationary frame of references. This unit is instrumented with several transducers such as miniature pressure transducers, strain gages, and proximity probes. The results show that for any propeller curve of a Kaplan turbine, the guide vane opening corresponding to the minimum pressure and strain fluctuations on the runner blade can be obtained by axial, torsion, and bending measurements on the shaft. Torsion measurements on the shaft could support index-testing in Kaplan turbines particularly for updating the cam-curve during the unit operation. Furthermore, a signature of every phenomenon observed on the runner blade signals, e.g., runner frequency, rotating vortex rope components, and rotor-stator interaction, is found in the data obtained from the shaft.

Place, publisher, year, edition, pages
MDPI, 2020
Keywords
prototype Kaplan turbine, load fluctuation on the runner, pressure measurement, strain measurement, axial strain, torsion strain, bending strain, indirect measurement
National Category
Fluid Mechanics and Acoustics Applied Mechanics
Research subject
Fluid Mechanics; Machine Design
Identifiers
urn:nbn:se:ltu:diva-82030 (URN)10.3390/s20247220 (DOI)000603243400001 ()33339455 (PubMedID)2-s2.0-85098144932 (Scopus ID)
Note

Validerad;2021;Nivå 2;2021-01-04 (alebob);

Finansiär: Svenskt Vattenkraftcentrum

Available from: 2020-12-17 Created: 2020-12-17 Last updated: 2023-09-05Bibliographically approved
Soltani Dehkharqani, A., Engström, F., Aidanpää, J.-O. & Cervantes, M. (2020). Experimental Investigation of a 10 MW Prototype Axial Turbine Runner: Vortex Rope Formation and Mitigation. Journal of Fluids Engineering, 142(10), Article ID 101212.
Open this publication in new window or tab >>Experimental Investigation of a 10 MW Prototype Axial Turbine Runner: Vortex Rope Formation and Mitigation
2020 (English)In: Journal of Fluids Engineering, ISSN 0098-2202, E-ISSN 1528-901X, Vol. 142, no 10, article id 101212Article in journal (Refereed) Published
Abstract [en]

The transient load fluctuations on the runner blades of prototype hydraulic turbines during load variations are one of the main causes of fatigue and eventual structural failure. A clear understanding of the dynamic loads on the runner blades is required to detect the source of the fluctuations. In this paper, an experimental investigation of vortex rope formation and mitigation in a prototype Kaplan turbine, namely, Porjus U9, is carried out. Synchronized unsteady pressure and strain measurements were performed on a runner blade during steady-state and load variation under off-cam condition. The normalized pressure fluctuation during load variations remained approximately within ±0.2 Pref for all the pressure transducers installed on the blade pressure side and is even slightly lower during the transient cycle. Higher pressure fluctuations were found on the blade suction side, approximately four times higher than that of on the pressure side. The synchronous and asynchronous components of the vortex rope were clearly observed at the low discharge operating point and transient cycles. The spectral analysis of the pressure signals showed that the synchronous component appears before the asynchronous component during the load reduction, and it lasts longer during the load increase. These frequencies slightly change during the load variation. In addition, the results proved that the strain fluctuation component on the runner blade arises from the synchronous component of the vortex rope at low discharge while the asynchronous component influence is negligible.

Place, publisher, year, edition, pages
American Society for Mechanical Engineers (ASME), 2020
Keywords
prototype Kaplan turbine, pressure measurement, strain measurement, Vortex rope
National Category
Other Mechanical Engineering Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics; Machine Design
Identifiers
urn:nbn:se:ltu:diva-80915 (URN)10.1115/1.4047793 (DOI)000567334100012 ()2-s2.0-85098222274 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-09-24 (alebob)

Available from: 2020-09-24 Created: 2020-09-24 Last updated: 2023-09-05Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-6016-6342

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