Efficiency prediction on a 2.5 MW wind turbine gearbox

This paper is a case study of the efficiency of a 2.5 MW wind turbine gearbox including the influence of each gearbox element: gear tooth geometry, rolling bearings and oil formulation. The power loss model used to predict the gearbox efficiency was previously validated with experimental results. The calculations showed that the efficiency of a wind turbine gearbox can be improved by selecting different wind turbine gear oil formulations, modifying gear tooth geometry. The energy savings can be even more significant if both gear tooth geometry and oil formulation are adequately selected.The authors gratefully acknowledge the funding supported by: National Funds through Fundação para a Ciência e a Tecnologia (FCT), under the project EXCL/SEM-PRO/0103/2012; COMPETE and National Funds through Fundação para a Ciência e a Tecnologia (FCT), under the project Incentivo/EME/LA0022/2014; Quadro de Referência Estratégico Nacional (QREN), through Fundo Europeu de Desenvolvimento Regional (FEDER), under the project NORTE-07-0124- FEDER-000009 - Applied Mechanics and Product Development; without whom this work would not be possible

Measurement of mean wear coefficient during gear tests under various operating conditions

Seven weartestswereconductedonanFZGgeartestingmachineinordertoascertaintheinfluence of basestock(PAOandmineral),specific film thicknessandcontactloadonthewearofspurgears,parti- cularlyonthewearcoefficient κ that isusedinArchard'slaw.Theresultsshowedthatloadmayhave some influence onthewearcoefficient. Theyalsoshowedthattheinfluence ofspecific film thicknesson wear isverynon-linear.Theinfluence ofbasestock,evenwithoilsofsimilarviscosity,isverysignificant, as muchasanyotherparameterinisolation.info:eu-repo/semantics/publishedVersio

High Pressure Characterization of the Viscous and Volumetric Behavior of Three Transmission Oils

Measurements of viscosity and density of three lubricating oils (two synthetic and one mineral) were performed. The density of these lubricants was measured at atmospheric pressure by means of a density measuring cell which works on the proven principle of the oscillating tube. Using the same device, the viscosity of these lubricants was measured at 0.1 MPa by using a rotational viscometer. The volumetric behavior of the tested lubricants at high pressure is also reported. Density was measured from 278.15 to 398.15 K up to 120 MPa with a high pressure vibrating tube densimeter. The isobaric thermal expansivity and the isothermal compressibility were determined with a Tammann–Tait equation. A falling body viscometer was used to determine the viscosity behavior at high pressure from 303.15 to 353.15 K up to 150 MPa. From the experimental data obtained in these measurements, the film pressure–viscosity coefficient of these lubricants was calculated and their ability to generate a lubricant film in rolling concentrated contacts was discussed.The authors gratefully acknowledge the funding through several projects and grants without whom this work would not have been possible: IACOBUS exchange program (2017); ENE2014-55489-C2-1-R and ENE2017-86425-C2-2-R cofinanced by the Spanish Ministry of Economy and Competitiveness and the European ERDF program; GRC ED431C 2016/001 financed by Xunta de Galicia (Spain); ED431E 2018/08 financed by Xunta de Galicia (Spain); Principia program JMLR of Xunta de Galicia (Spain); NORTE-01-0145-FEDER-000022—SciTech—Science and Technology for Competitive and Sustainable Industries, cofinanced by Programa Operacional Regional do Norte (NORTE2020), through Fundo Europeu de Desenvolvimento Regional (FEDER); LAETA under the project UID/EMS/50022/2013.S

Power loss of FZG gears lubricated with wind turbine gear oil using ionic liquid additive

This work presents a study of the tribological behaviour of a mineral fully-formulated wind turbine gear oil additised with [BMP][NTf2] ionic liquid. The target application are the wind turbine gearboxes, thus the fully formulated oil with and without ionic liquid additive was tested in a rolling bearings test rig to measure the thrust rolling bearing torque loss and was also tested in a FZG gear test rig to measure the gears torque loss at operating conditions similar to the observed in a wind turbine gearbox. The results show that a wind turbine gear oil additised with ionic liquid can reduce the torque loss and improve the gearbox efficiency while producing less wear particles as observed in the oil analysis.The authors thank to the Ministry of Science and Innovation (Spain) and to the Foundation for the Promotion in Asturias of the Applied Scientific Research and Technology (FICYT) for supporting this research within the framework of the Research Projects WINDTRIB (DPI2010-18166) and GRUPIN14-023, respectively. The authors thank to Repsol S.A. that provided the wind turbine gear oil. The authors gratefully acknowledge the funding supported by: National Funds through Fundação para a Ciência e a Tecnologia (FCT), under the project EXCL/SEMPRO/ 0103/2012; COMPETE and National Funds through Fundação para a Ciência e a Tecnologia (FCT), under the project Incentivo/EME/LA0022/2014; Quadro de Referência Estratégico Nacional (QREN), through Fundo Europeu de Desenvolvimento Regional (FEDER), under the project NORTE-07-0124-FEDER- 000009 - Applied Mechanics and Product Development; without whom this work would not be possible

Thermophysical and Tribological Properties of Highly Viscous Biolubricants

Two new highly viscous biodegradable oils are investigated for use in wind turbine gearboxes (BIO-G00) and in mechanical transmissions of agricultural tractors (BIO-G02). Studies on their thermophysical and tribological properties were performed. High-pressure–viscosity measurements were obtained up to 250 MPa and 363.15 K using a falling-body apparatus. The viscosity of BIO-G00 and BIO-G02 reaches maximum values of 14720 and 7072 mPa·s, respectively. The film thickness and the tribological performance, from boundary to full-fluid lubrication regimes, under a slide-to-roll ratio of 5% obtained in an EHD2 ball-on-disk test rig are reported. Film thickness has also been computed through the Hamrock and Dowson equation, considering the inlet shear heating (thermal correction factor) due to the high viscosity of both biolubricants. Differences between the experimental and theoretical film thicknesses are around 4% at 353.15 K and 14% at 303.15 K for both oils. The universal pressure–viscosity coefficients, αfilm, for both oils are lower than those of other mineral and synthetic oils. Higher friction coefficients are obtained for BIO-G00 in all of the studied lubrication regimes for the different rough disks and in the entire temperature range. A suitable wetting behavior on steel surfaces is observed for both selected oils.Spanish Ministry of Economy and Competitiveness and the Xunta de Galicia have supported this work through GRC ED431C 2020/10 and ENE2017-86425-C2-2-R projects. The authors are grateful to the BIOVESIN (PSE-420000-2008-4) partners for the advice and for providing them the samples of the vegetable formulated oils and the reference lubricants. Dr. M.J.G.G. acknowledges a postdoctoral fellowship (ED481B-2019-015) from the Xunta de Galicia (Spain), and Dr. L.d.R. acknowledges the financial support through the Margarita Salas program (Ministry of Universities, Spain). The authors express their gratitude to Dr. K.R. Harris (University of New South Wales, Australia) for his high-pressure–viscosity study of DiPEiC9 and also to M.A. Marcos from the University of Vigo for his help with rheology tests.S

Surface fitting of an involute spur gear tooth flank roughness measurement to its nominal shape

A method for fitting a topography measured on an involute spur gear tooth flank to its nominal shape is proposed, so that the exact position along the length of the tooth from which the measured surface originates can be determined, and so that the nominal shape of the surface can be subtracted prior to roughness parameters calculation.info:eu-repo/semantics/publishedVersio

Friction torque in thrust ball bearings lubricated with polymer greases of different thickener content

In this work a series of experimental tests were performed in thrust ball bearings lubricated with polymer greases. The tested greases were formulated with the same base oil but different thickener content. A multi-purpose lithium thickened grease was also tested as reference. The friction torque was measured at constant temperature and load, while varying the rotational speed. The coefficients of friction under boundary and full film lubrication were numerically calculated through the optimization of a rolling bearing friction torque model to the experimental measurements. The results show that the higher the thickener content, the smaller is the friction torque generated by the lubricating greases, phenomenon which was found to be especially important at low speeds and low specific film thickness.info:eu-repo/semantics/publishedVersio

Effect of the addition of coated SiO2 nanoparticles on the tribological behavior of a low-viscosity polyalphaolefin base oil

This work reports tribological properties of PAO6 containing SiO2 nanoparticles modified with stearic-acid (SiO2-SA) as additives at concentrations (0.05, 0.10, 0.20, 0.30) wt% and the same concentration of SA as a dispersant. Tribological experiments were performed at 120 °C in pure sliding and rolling-sliding conditions (5% slide-to-roll ratio). All nanolubricants have better anti-friction capabilities than PAO6. The optimum concentration for friction reduction was 0.30 wt% for both tribological conditions. The best anti-wear results for the specimens tested in pure sliding conditions were achieved with PAO6 + 0.20 wt% SiO2-SA with reductions of 55%, 86% and 92%, in wear track width, wear track depth and wear area, respectively. Tribological mechanisms of the nanoparticles have been analyzed through roughness measurements, concluding that polishing, tribofilm and adsorption of the additives occurThis research is supported by Xunta de Galicia (ED431C 2020/10), by MCIN/AEI/10.13039/501100011033 through the PID2020-112846RB-C22 project and by LAETA, Portugal, under project UID/50022/2020. JMLdR is grateful for financial support through the Margarita Salas program, funded by MCIN/AEI/10.13039/501100011033 and “NextGenerationEU/PRTR”. FM acknowledges a IACOBUS grant to the European Grouping for Territorial Cooperation Galicia-North of Portugal (GNP-EGTC). Furthermore, authors are also grateful to Repsol Lubricants for providing the PAO6 base oil and to RIAIDT-USC for its analytical facilitiesS