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| 2. |
- Gantasala, Sudhakar, et al.
(författare)
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Numerical Investigation of the Aeroelastic Behavior of a Wind Turbine with Iced Blades
- 2019
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 12:12
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Dahlén, Leon, et al.
(författare)
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Vegetable and synthetic hydraulic fluids to improve the overall efficiency of a hydrostatic transmission
- 2001
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Ingår i: Journal of Synthetic Lubrication. - : Wiley. - 0265-6582 .- 1557-6841. ; 17:4, s. 263-276
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the investigation reported here was to determine whether or not a hydrostatic transmission can act as an alternative to a conventional one, and, if so, to ascertain to what extent the fluid type contributes to an improvement in the efficiency of the hydrostatic transmission. The results presented in this paper are derived from an experimental field test of the hydrostatic transmission of a belt conveyor. This belt conveyor is one part in an ore-transport line at LKAB mining company in Kiruna. The hydrostatic transmission replaced a conventional transmission consisting of an electric motor, a belt drive and a gearbox. The hydrostatic transmission was operated using three different hydraulic fluids: Shell Tellus TX 68, a conventional mineral oil; Mobil SHC 526, a synthetic fluid; and Binol Hydrap II, a vegetable fluid. All fluids have the same ISO viscosity grade, VG 68. The measurements on the transmission show a 3% overall efficiency improvement when using vegetable and synthetic hydraulic fluids compared with the mineral oil. The current at the start of the transmission was reduced by a factor of 6, compared to that of the conventional transmission. The installed 110 kW electric motor was replaced with one of 55 kW. The test also showed that a closer study of all operating conditions, and a selection of components suited to the size of the load, can improve the overall efficiency of the hydrostatic transmission.
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| 4. |
- Cervantes, Michel, et al.
(författare)
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Porjus U9A full-scale hydropower research facility
- 2008
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Ingår i: Hydro technology and the evironment for the new century. - Foz do Iguassu.
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Konferensbidrag (refereegranskat)abstract
- Hydropower still faces complex scientific and technical challenges in order to secure the availability and reliability of the power plants despite more than a century of development. The main challenge is due to new market constrains such as electrical market deregulation and introduction of renewable sources of energy. The major problem is related to the dynamic of the rotor involving several fields: hydraulics, power engineering and mechanics. On the other side, the large and growing hydropower world market represents an opportunity for technically advanced companies offering better efficiency. The difficulty to scale rigorously any technical advance makes full-scale experiment a necessity. World unique facilities are available at Porjus, Sweden, for this purpose. The Porjus Hydropower Centre is composed of a Francis (U8) and a Kaplan (U9) turbine of 10 MW, each exclusively dedicated to education, research and development. In order to further investigate specific issues related to availability and reliability, a project was initiated in 2006. The main objective is to make U9 a full-scale hydropower laboratory able firstly to furnish the necessary data for the development of rotor-dynamic models but also turbines and bearings. To this purposes more than 200 sensors have been installed to measure displacements, forces, pressure, film thickness, strains... The work presents an overview of the newly upgrade facility as well as some of the problems faced during the instrumentation of the machine.
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| 5. |
- Mill, O., et al.
(författare)
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Analysis and development of hydro power research : synthesis within Swedish Hydro Power Centre
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The market for hydropower re-investments in Sweden is approx 2.5 billion SEK/yr the coming decade. Large investments will also be carried out in Swedish tailing dams. This will result in challenging projects and need of experts. A crucial factor for a successful management of these challenges is the supply of engineers and researchers with hydro power and dam skills and knowledge. Swedish Hydro Power Centre (Svenskt vattenkraftcentrum, SVC) is a competence centre for university education and research environments within hydro power and mining dams. SVC comprises of two knowledge areas: Hydraulic Engineering and Hydro Turbines and Generators, respectively. SVC builds high-quality and long term sustainable knowledge at selected universities...
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| 6. |
- Khodadad, Davood, et al.
(författare)
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Full-field 3D deformation measurement : Comparison between speckle phase and displacement evaluation
- 2016
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Ingår i: Applied Optics. - : Optical Society of America. - 1559-128X .- 2155-3165 .- 0003-6935 .- 1539-4522. ; 55:27, s. 7735-7743
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this paper is to describe a full-field deformation measurement method based on 3D speckle displacements. The deformation is evaluated from the slope of the speckle displacement function that connects the different reconstruction planes. For our experiment, a symmetrical arrangement with four illuminations parallel to the planes (x,z) and (y,z) was used. Four sets of speckle patterns were sequentially recorded by illuminating an object from the four directions, respectively. A single camera is used to record the holograms before and after deformations. Digital speckle photography is then used to calculate relative speckle displacements in each direction between two numerically propagated planes. The 3D speckle displacements vector is calculated as a combination of the speckle displacements from the holograms recorded in each illumination direction. Using the speckle displacements, problems associated with rigid body movements and phase wrapping are avoided. In our experiment, the procedure is shown to give the theoretical accuracy of 0.17 pixels yielding the accuracy of 2 × 10-3 in the measurement of deformation gradients
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| 7. |
- Löfstrand, Magnus, et al.
(författare)
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A model for predicting and monitoring industrial system availability
- 2012
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Ingår i: International Journal of Product Development. - Bucks, United Kingdom : InderScience Publishers. - 1477-9056 .- 1741-8178. ; 16:2, s. 140-157
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes the integration of a sensor data stream monitoring system into a proposed functional product model capable of predicting functional availability. Such monitoring systems enable predictive maintenance to be carried out pre-emptive maintenance that is scheduled in response to imminent hardware failure and are in widespread use in industry. The industrial motivation for this research is that agreed upon system availability is a critical element of any business-to-business agreement regarding functional sales. Such a model is important when making strategic choices regarding FPs and can be used to develop a high availability product design through simulation driven development, as well as to provide operational decision support that reflects the current reality to enable optimal availability to be achieved in practice. The proposed model integrates hardware, support system and monitoring system models, and is able to incorporate actual operational data. It has been partly verified based on previous research.
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| 8. |
- Reed, Sean, 1982-, et al.
(författare)
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Quantified economic and environmental values through Functional Productization : A simulation approach
- 2018
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Ingår i: Environmental impact assessment review. - : Elsevier. - 0195-9255 .- 1873-6432. ; 70, s. 71-80
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Tidskriftsartikel (refereegranskat)abstract
- Industrial companies rely on hardware and services from external providers to deliver functions that are critical to their operations, increasingly demanding solutions that not only meet technical and availability requirements but are sustainable too. Traditionally, industrial companies choose and purchase hardware and maintenance support to fulfil their functional requirements. An alternative arrangement, known as Functional Product (FP), involves external providers supplying customers with the functionality they require through contracts that specify guaranteed functional availability whilst giving providers freedom to choose and retain ownership of the supplied hardware and services. This paper describes an innovative simulation modelling and optimization approach to quantitatively compare economic and environmental values resulting from transition from traditional to FP arrangements. The approach is demonstrated through the analysis of a scenario involving a hydraulic drive system provider and set of customers in Sweden, with the results exhibiting simultaneous improvement in economic and environmental values at each stage of the transition.
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| 9. |
- Simmons, Gregory F, et al.
(författare)
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Steady state and dynamic characteristics for guide bearings of a hydro-electric unit
- 2014
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Ingår i: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology. - : SAGE Publications. - 1350-6501 .- 2041-305X. ; 228:8, s. 836-848
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Tidskriftsartikel (refereegranskat)abstract
- Experiments are conducted using a 10-MW Kaplan hydropower machine which is outfitted with an extensive array of sensors to determine oil film thickness, pad load and oil temperature in all three guide bearings as well as motion of the shaft in relation to both the bearing housings and the concrete foundation. Test results for all journal bearings are compared to a commercial rotor dynamics model and results for the central journal bearing are compared to a multi-physics model to provide insight into the machine's steady state and dynamic characteristics and their variations during normal operation.
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| 10. |
- Soltani Dehkharqani, Arash, et al.
(författare)
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Fluid added polar inertia and damping for the torsional vibration of a Kaplan turbine model runner considering multiple perturbations
- 2019
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Ingår i: IOP Conference Series. - : Institute of Physics (IOP).
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Konferensbidrag (refereegranskat)abstract
- 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.
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