Change search
Link to record
Permanent link

Direct link
BETA
Aidanpää, Jan-OlovORCID iD iconorcid.org/0000-0001-6016-6342
Alternative names
Publications (10 of 102) Show all publications
Gantasala, S. & Aidanpää, J.-O. (2019). A Preliminary Experiment to Excite and Identify Modal Frequencies of a Rotor in the Rotating Frame of Reference. In: Katia Lucchesi Cavalca, Hans Ingo Weber (Ed.), Proceedings of the 10th International Conference on Rotor Dynamics – IFToMM: . Paper presented at 10th International Conference on Rotor Dynamics – IFToMM, SEP 23-27 2018 (pp. 265-277). Cham: Springer
Open this publication in new window or tab >>A Preliminary Experiment to Excite and Identify Modal Frequencies of a Rotor in the Rotating Frame of Reference
2019 (English)In: Proceedings of the 10th International Conference on Rotor Dynamics – IFToMM / [ed] Katia Lucchesi Cavalca, Hans Ingo Weber, Cham: Springer, 2019, p. 265-277Conference paper, Published paper (Refereed)
Abstract [en]

The current work uses two types of excitation on a rotating shaft to identify its modal frequencies. The first one is a non-contact excitation where an oscillating magnet is placed near the shaft, eddy currents generated by the oscillating magnetic field excites vibrations in the shaft. In the second type of excitation, a miniature electrodynamical exciter powered by a decoder amplifier board is placed on the shaft to excite vibrations with predefined frequencies in a signal (mp3 format) stored on the USB flash drive connected to the board. The shaft is rotated at different speeds and vibration accelerations are measured using a small data logger placed on the shaft while excited using these two excitation systems. These two types of asynchronous excitation on the shaft excites both forward and backward whirl vibration modes of the rotor system. The modal frequencies are identified at the peak amplitudes in the waterfall plots of the measured vibration accelerations to a chirp excitation of the shaft. A Campbell diagram is plotted with the identified modal frequencies of the shaft in the rotating frame of reference.

Place, publisher, year, edition, pages
Cham: Springer, 2019
Series
Mechanisms and Machine Science, ISSN 2211-0984 ; 62
National Category
Other Mechanical Engineering
Research subject
Computer Aided Design
Identifiers
urn:nbn:se:ltu:diva-70522 (URN)10.1007/978-3-319-99270-9_19 (DOI)2-s2.0-85051798726 (Scopus ID)978-3-319-99269-3 (ISBN)978-3-319-99270-9 (ISBN)
Conference
10th International Conference on Rotor Dynamics – IFToMM, SEP 23-27 2018
Available from: 2018-08-21 Created: 2018-08-21 Last updated: 2018-08-29Bibliographically approved
Gantasala, S. & Aidanpää, J.-O. (2019). A Preliminary Experiment to Excite and Identify Modal Frequencies of a Rotor in the Rotating Frame of Reference. In: Cavalca, Katia Lucchesi; Weber, Hans Ingo (Ed.), Proceedings of the 10th International Conference on Rotor Dynamics: IFToMM. Paper presented at 10th International Conference on Rotor Dynamics, 23-27 September 2018, Rio de Janeiro, Brazil (pp. 265-277). Springer, 3
Open this publication in new window or tab >>A Preliminary Experiment to Excite and Identify Modal Frequencies of a Rotor in the Rotating Frame of Reference
2019 (English)In: Proceedings of the 10th International Conference on Rotor Dynamics: IFToMM / [ed] Cavalca, Katia Lucchesi; Weber, Hans Ingo, Springer, 2019, Vol. 3, p. 265-277Conference paper, Published paper (Refereed)
Abstract [en]

The current work uses two types of excitation on a rotating shaft to identify its modal frequencies. The first one is a non-contact excitation where an oscillating magnet is placed near the shaft, eddy currents generated by the oscillating magnetic field excites vibrations in the shaft. In the second type of excitation, a miniature electrodynamical exciter powered by a decoder amplifier board is placed on the shaft to excite vibrations with predefined frequencies in a signal (mp3 format) stored on the USB flash drive connected to the board. The shaft is rotated at different speeds and vibration accelerations are measured using a small data logger placed on the shaft while excited using these two excitation systems. These two types of asynchronous excitation on the shaft excites both forward and backward whirl vibration modes of the rotor system. The modal frequencies are identified at the peak amplitudes in the waterfall plots of the measured vibration accelerations to a chirp excitation of the shaft. A Campbell diagram is plotted with the identified modal frequencies of the shaft in the rotating frame of reference.

Place, publisher, year, edition, pages
Springer, 2019
Series
Mechanisms and Machine Science, ISSN 2211-0984, E-ISSN 2211-0992
Keywords
Modal frequency, Rotor Excitation, Campbell diagram, Rotating frame of reference
National Category
Applied Mechanics Other Mechanical Engineering
Research subject
Computer Aided Design
Identifiers
urn:nbn:se:ltu:diva-70964 (URN)10.1007/978-3-319-99270-9_19 (DOI)978-3-319-99269-3 (ISBN)978-3-319-99270-9 (ISBN)
Conference
10th International Conference on Rotor Dynamics, 23-27 September 2018, Rio de Janeiro, Brazil
Available from: 2018-09-25 Created: 2018-09-25 Last updated: 2019-11-22Bibliographically approved
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: 2019-11-26Bibliographically approved
Gantasala, S., Tabatabaei, N., Cervantes, M. & Aidanpää, J.-O. (2019). Numerical Investigation of the Aeroelastic Behavior of a Wind Turbine with Iced Blades. Energies, 12(12), Article ID 2422.
Open this publication in new window or tab >>Numerical Investigation of the Aeroelastic Behavior of a Wind Turbine with Iced Blades
2019 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 12, article id 2422Article in journal (Refereed) Published
Abstract [en]

Wind turbines installed in cold-climate regions are prone to the risks of ice accumulation which affects their aeroelastic behavior. The studies carried out on this topic so far considered icing in a few sections of the blade, mostly located in the outer part of the blade, and their influence on the loads and power production of the turbine are only analyzed. The knowledge about the influence of icing in different locations of the blade and asymmetrical icing of the blades on loads, power, and vibration behavior of the turbine is still not matured. To improve this knowledge, multiple simulation cases are needed to run with different ice accumulations on the blade considering structural and aerodynamic property changes due to ice. Such simulations can be easily run by automating the ice shape creation on aerofoil sections and two-dimensional (2-D) Computational Fluid Dynamics (CFD) analysis of those sections. The current work proposes such methodology and it is illustrated on the National Renewable Energy Laboratory (NREL) 5 MW baseline wind turbine model. The influence of symmetrical icing in different locations of the blade and asymmetrical icing of the blade assembly is analyzed on the turbine’s dynamic behavior using the aeroelastic computer-aided engineering tool FAST. The outer third of the blade produces about 50% of the turbine’s total power and severe icing in this part of the blade reduces power output and aeroelastic damping of the blade’s flapwise vibration modes. The increase in blade mass due to ice reduces its natural frequencies which can be extracted from the vibration responses of the turbine operating under turbulent wind conditions. Symmetrical icing of the blades reduces loads acting on the turbine components, whereas asymmetrical icing of the blades induces loads and vibrations in the tower, hub, and nacelle assembly at a frequency synchronous to rotational speed of the turbine.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
wind turbine, icing, simulation, aeroelastic behavior, CFD
National Category
Energy Engineering Fluid Mechanics and Acoustics Other Mechanical Engineering
Research subject
Computer Aided Design; Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-71180 (URN)10.3390/en12122422 (DOI)000473821400195 ()
Note

Validerad;2019;Nivå 2;2019-07-05 (johcin)

Available from: 2018-10-12 Created: 2018-10-12 Last updated: 2019-10-21Bibliographically 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: 2019-11-26Bibliographically approved
Gantasala, S., Luneno, J.-C. & Aidanpää, J.-O. (2018). Identification of ice mass accumulated on wind turbine blades using its natural frequencies. Wind Engineering: The International Journal of Wind Power, 42(1), 66-84
Open this publication in new window or tab >>Identification of ice mass accumulated on wind turbine blades using its natural frequencies
2018 (English)In: Wind Engineering: The International Journal of Wind Power, ISSN 0309-524X, E-ISSN 2048-402X, Vol. 42, no 1, p. 66-84Article in journal (Refereed) Published
Abstract [en]

This work demonstrates a technique to identify information about the ice mass accumulation on wind turbine blades using its natural frequencies, and these frequencies reduce differently depending on the spatial distribution of ice mass along the blade length. An explicit relation to the natural frequencies of a 1-kW wind turbine blade is defined in terms of the location and quantity of ice mass using experimental modal analyses. An artificial neural network model is trained with a data set (natural frequencies and ice masses) generated using that explicit relation. After training, this artificial neural network model is given an input of natural frequencies of the iced blade (identified from experimental modal analysis) corresponding to 18 test cases, and it identified ice masses’ location and quantity with a weighted average percentage error value of 17.53%. The proposed technique is also demonstrated on the NREL 5-MW wind turbine blade data.

Place, publisher, year, edition, pages
Sage Publications, 2018
Keywords
Wind turbine blade, ice detection, natural frequency, experimental modal analysis, artificial neural network
National Category
Applied Mechanics Other Mechanical Engineering
Research subject
Computer Aided Design
Identifiers
urn:nbn:se:ltu:diva-65213 (URN)10.1177/0309524X17723207 (DOI)000419838000005 ()2-s2.0-85040450029 (Scopus ID)
Projects
Wind power in cold climates
Funder
Swedish Energy Agency
Note

Validerad;2018;Nivå 2;2018-01-23 (andbra)

Available from: 2017-08-21 Created: 2017-08-21 Last updated: 2019-10-21Bibliographically approved
Gantasala, S., Luneno, J.-C. & Aidanpää, J.-O. (2017). Investigating How an Artificial Neural Network Model Can Be Used to Detect Added Mass on a Non-Rotating Beam Using Its Natural Frequencies: A Possible Application for Wind Turbine Blade Ice Detection. Energies, 10(2), Article ID 184.
Open this publication in new window or tab >>Investigating How an Artificial Neural Network Model Can Be Used to Detect Added Mass on a Non-Rotating Beam Using Its Natural Frequencies: A Possible Application for Wind Turbine Blade Ice Detection
2017 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 10, no 2, article id 184Article in journal (Refereed) Published
Abstract [en]

Structures vibrate with their natural frequencies when disturbed from their equilibrium position. These frequencies reduce when an additional mass accumulates on their structures, like ice accumulation on wind turbines installed in cold climate sites. The added mass has two features: the location and quantity of mass. Natural frequencies of the structure reduce differently depending on these two features of the added mass. In this work, a technique based on an artificial neural network (ANN) model is proposed to identify added mass by training the neural network with a dataset of natural frequencies of the structure calculated using different quantities of the added mass at different locations on the structure. The proposed method is demonstrated on a non-rotating beam model fixed at one end. The length of the beam is divided into three zones in which different added masses are considered, and its natural frequencies are calculated using a finite element model of the beam. ANN is trained with this dataset of natural frequencies of the beam as an input and corresponding added masses used in the calculations as an output. ANN approximates the non-linear relationship between these inputs and outputs. An experimental setup of the cantilever beam is fabricated, and experimental modal analysis is carried out considering a few added masses on the beam. The frequencies estimated in the experiments are given as an input to the trained ANN model, and the identified masses are compared against the actual masses used in the experiments. These masses are identified with an error that varies with the location and the quantity of added mass. The reason for these errors can be attributed to the unaccounted stiffness variation in the beam model due to the added mass while generating the dataset for training the neural network. Therefore, the added masses are roughly estimated. At the end of the paper, an application of the current technique for detecting ice mass on a wind turbine blade is studied. A neural network model is designed and trained with a dataset of natural frequencies calculated using the finite element model of the blade considering different ice masses. The trained network model is tested to identify ice masses in four test cases that considers random mass distributions along the blade. The neural network model is able to roughly estimate ice masses, and the error reduces with increasing ice mass on the blade.

Place, publisher, year, edition, pages
MDPI, 2017
Keywords
artificial neural network, ice mass, detection, wind turbine blade, natural frequency
National Category
Applied Mechanics Other Mechanical Engineering
Research subject
Computer Aided Design
Identifiers
urn:nbn:se:ltu:diva-61885 (URN)10.3390/en10020184 (DOI)000395469200038 ()2-s2.0-85014095862 (Scopus ID)
Projects
Wind power in cold climates
Funder
Swedish Energy Agency
Note

Validerad; 2017; Nivå 2; 2017-02-15 (andbra)

Available from: 2017-02-09 Created: 2017-02-09 Last updated: 2019-10-21Bibliographically approved
Soltani Dehkharqani, A., Cervantes, M. & Aidanpää, J.-O. (2017). Numerical analysis of fluid-added parameters for the torsional vibration of a Kaplan turbine model runner. Advances in Mechanical Engineering, 9(10), Article ID 1687814017732893.
Open this publication in new window or tab >>Numerical analysis of fluid-added parameters for the torsional vibration of a Kaplan turbine model runner
2017 (English)In: Advances in Mechanical Engineering, ISSN 1687-8132, E-ISSN 1687-8140, Vol. 9, no 10, article id 1687814017732893Article in journal (Refereed) Published
Abstract [en]

The impact of fluid on the runner of a hydraulic turbine is a recurrent problem. Fully coupled fluid-structure simulations are extremely time consuming. Thus, an alternative method is required to estimate this interaction to perform a reliable rotor dynamic analysis. In this paper, numerical estimations of the added inertia, damping and stiffness for a Kaplan turbine model runner are presented using transient-flow simulations. A single-degree-of-freedom model was assumed for the fluid-runner interaction, and the parameters were estimated by applying a harmonic disturbance to the angular velocity of the runner. The results demonstrate that the added inertia and damping are important, whereas the stiffness is negligible. The dimensionless added polar inertia is 23-27% of the reference value (ρR5). Damping significantly contributes to the moment at low excitation frequencies, whereas the inertia becomes dominant at higher frequencies.

Place, publisher, year, edition, pages
Sage Publications, 2017
National Category
Fluid Mechanics and Acoustics Other Mechanical Engineering
Research subject
Fluid Mechanics; Computer Aided Design
Identifiers
urn:nbn:se:ltu:diva-66314 (URN)10.1177/1687814017732893 (DOI)000413891200001 ()2-s2.0-85033435074 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-11-09 (andbra)

Available from: 2017-10-30 Created: 2017-10-30 Last updated: 2019-11-26Bibliographically approved
Thiery, F., Gantasala, S. & Aidanpää, J.-O. (2017). Numerical evaluation of multilobe bearings using the Spectral Method. Advances in Mechanical Engineering, 9(7)
Open this publication in new window or tab >>Numerical evaluation of multilobe bearings using the Spectral Method
2017 (English)In: Advances in Mechanical Engineering, ISSN 1687-8132, E-ISSN 1687-8140, Vol. 9, no 7Article in journal (Refereed) Published
Abstract [en]

Hydropower rotors and pumps have the specificity to be oriented vertically, meaning that the bearing forces have to be evaluated at each time-step depending on the position of the rotor for dynamical analyses. If the bearing forces cannot be evaluated analytically, a suitable numerical method should be used to calculate the pressure distribution over the bearing domain. This process can be computationally expensive as it should be performed for each discrete time-step. As a result, a comparison between the spectral method, the finite difference method, and the finite element method is performed to investigate which method is more adapted to dynamical analysis of the bearing. It is observed that the spectral method has the advantage of having a reasonable simulation time for any eccentricity magnitude with a moderate number of interpolation points. However, this method should be restricted to simple bearing models such as plain bearings or multilobe bearings due to the advantage of finding a global numerical solution directly on the entire bearing/pad domain

Place, publisher, year, edition, pages
Sage Publications, 2017
National Category
Applied Mechanics Other Mechanical Engineering
Research subject
Computer Aided Design
Identifiers
urn:nbn:se:ltu:diva-63122 (URN)10.1177/1687814017707135 (DOI)000405521000001 ()2-s2.0-85026484512 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-08-16 (andbra)

Available from: 2017-04-24 Created: 2017-04-24 Last updated: 2018-07-10Bibliographically approved
Gantasala, S., Luneno, J.-C., Aidanpää, J.-O. & Cervantes, M. (2016). Aeroelastic simulations of wind turbine using 13 DOF rigid beam model (ed.). Paper presented at International Symposium on Transport Phenomena and Dynamics of Rotating Machinery : 10/04/2016 - 15/04/2016. Paper presented at International Symposium on Transport Phenomena and Dynamics of Rotating Machinery : 10/04/2016 - 15/04/2016.
Open this publication in new window or tab >>Aeroelastic simulations of wind turbine using 13 DOF rigid beam model
2016 (English)Conference paper, Oral presentation only (Refereed)
Abstract [en]

The vibration behavior of wind turbine substructures is mainly dominated by their first few vibration modes because wind turbines operate at low rotational speeds. In this study, 13 degrees of freedom (DOF) model of a wind turbine is derived considering fundamental vibration modes of the tower and blades which are modelled as rigid beams with torsional springs attached at their root. Linear equations of motion (EOM) governing the structural behavior of wind turbines are derived by assuming small amplitude vibrations. This model is used to study the coupling between the structural and aerodynamic behavior of NREL 5 MWmodel wind turbine. Aeroelastic natural frequencies of the current model are compared with the results obtained from the finite element model of this wind turbine. Quasi-steady aerodynamic loads are calculated considering wind velocity changes due to height and tower shadow effects. In this study, vibration responses are simulated at various wind velocities. The derived 13 DOF simplified model of the wind turbine enables to simulate the influence ofchange in parameters and operating conditions on vibration behavior with less computational effort. Besides that, the results of the simplified models can be interpreted with much ease.

National Category
Other Mechanical Engineering Fluid Mechanics and Acoustics
Research subject
Computer Aided Design; Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-32570 (URN)71b9860a-5951-4f01-890c-78a58cd41753 (Local ID)71b9860a-5951-4f01-890c-78a58cd41753 (Archive number)71b9860a-5951-4f01-890c-78a58cd41753 (OAI)
Conference
International Symposium on Transport Phenomena and Dynamics of Rotating Machinery : 10/04/2016 - 15/04/2016
Note
Godkänd; 2016; 20160512 (sudgan)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2019-10-21Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6016-6342

Search in DiVA

Show all publications