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- 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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- Cupillard, Samuel, et al.
(författare)
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3D thermodynamic analysis of a textured slider
- 2008
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Ingår i: Proceedings of NORDTRIB 2008, 13th Nordic Symposium on Tribology. - Tampere : Tampere University of Technology. - 9789521519598
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Konferensbidrag (refereegranskat)abstract
- Analysis of a 3D inlet textured slider bearing with a temperature dependent fluid is performed. Numerical simulations are carried out for a laminar and steady flow. Hot and cold lubricant mixing in the groove is modelled and examined for different operating conditions. Thermohydrodynamic performance of the bearing is analysed for different texture lengths. Results show that texture has a stronger and positive influence on load carrying capacity when thermal effects are considered. This beneficial effect is at a maximum for the longest dimples with a length shorter than the pad length. Texture is also beneficial for the load carrying capacity when the sliding speed and inlet flow rate are varied: with an appropriate supply mass flow, load carrying capacity can be increased by 6-7% at low sliding speeds.
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- Cupillard, Samuel, et al.
(författare)
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3D thermohydrodynamic analysis of a textured slider
- 2009
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Ingår i: Tribology International. - : Elsevier BV. - 0301-679X .- 1879-2464. ; 42:10, s. 1487-1495
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Tidskriftsartikel (refereegranskat)abstract
- Analysis of a 3D inlet textured slider bearing with a temperature dependent fluid is performed. Numerical simulations are carried out for a laminar and steady flow. Hot and cold lubricant mixing in the groove is modelled and examined for different operating conditions. Thermohydrodynamic performance of the bearing is analysed for different texture lengths. Results show that texture has a stronger and positive influence on load carrying capacity when thermal effects are considered. This beneficial effect is at a maximum for the longest dimples with a length shorter than the pad length. Texture is also beneficial for the load carrying capacity when the sliding speed and inlet flow rate are varied. The load carrying capacity of the slider can be increased by up to 16% in severe operating conditions (high sliding speed).
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- Cupillard, Samuel, et al.
(författare)
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A CFD study of a finite textured journal bearing
- 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
- An analysis of a lubricated journal bearing is performed with special attention to the influence of textured surfaces which may improve hydrodynamic performance. The bearing is subjected to an external applied load and the force balance is fulfilled with the force of the flow acting on the bearing. The position of the shaft is fixed whereas the bearing, centred at the starting time, moves under the forces until equilibrium is reached. A mesh deformation technique is used with CFD (Computational Fluid Dynamics) in order to perform the simulations. The flow is laminar, isothermal, three-dimensional (3D) and unsteady. Cavitation is taken into account. Results are analysed with smooth and textured surfaces on the bearing. Friction force and eccentricity ratio are compared for different configurations.It is found that shallow grooves under light loading (ε < 0.15) enhance the minimum film thickness while reducing the friction force. Under high loading (ε > 0.5), deep grooves are able to reduce the friction force despite a reduced minimum film thickness. For the second case, the predicted performance is superior to those of a smooth journal bearing with thinner lubricant.
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- Cupillard, Samuel, et al.
(författare)
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Computational fluid dynamics analysis of a journal bearing with surface texturing
- 2008
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Ingår i: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology. - 1350-6501 .- 2041-305X. ; 222:2, s. 97-107
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Tidskriftsartikel (refereegranskat)abstract
- An analysis of a lubricated conformal contact is carried out to study the effect of surface texture on bearing friction and load carrying capacity using computational fluid dynamics. The work focuses on a journal bearing with several dimples. Two- and three-dimensional bearing geometries are considered. The full Navier-Stokes equations are solved under steady-state conditions with a multi-phase flow cavitation model. The coefficient of friction can be reduced if a texture of suitable geometry is introduced. This can be achieved either in the region of maximum hydrodynamic pressure for a bearing with high eccentricity ratio or just downstream of the maximum film for a bearing with low eccentricity ratio. An additional pressure build-up produced as a result of the surface texture has been shown at low eccentricity ratios.
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