The second part of the study presents an extensive campaign of experimental tests in an FZG test rig. An average coefficient of friction between meshing gears was devised from the experimental ...results. Several aspects regarding the meshing gears power loss are discussed such as gear loss factor, coefficient of friction and the influence of gear oil formulation (wind turbine gear oils).
•Power loss in gears lubricated with wind turbine gear oils in FZG test rig.•Comparison between numerical predictions and experimental results.•Comparison of different gear loss factor formulations.•Coefficient of friction between gear teeth for wind turbine gear oils.
This work presents a study of the tribological behavior of a mineral fully-formulated wind turbine gear oil additised with BMPNTf2 ionic liquid. The target application is 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.
•Tribological behavior of a mineral wind turbine gear oil additised with BMPNTf2 ionic liquid.•Torque loss of rolling bearings was measured in a dedicated test rig.•Torque loss and wear tests were performed with type C14 FZG gears.•The addition of the ionic liquid decrease torque loss, power loss and wear, and increase efficiency.
This work is devoted to the analysis, modeling and validation of gearbox power loss, considering the influence of the gears, rolling bearings and seals, the influence of the operating conditions, ...lubricant formulation and the lubrication method.
The first part of this work a rolling bearing torque loss model is calibrated for several wind turbine gear oils and for ball and roller contacts. The results achieved clarify the importance of a rolling bearing in a gearbox power loss.
In the second part of this work will be presented the same approach for gears. The final part will converge in the application of findings in two full gearboxes, a planetary and a parallel axis gearbox, both in multiplying configuration.
•Power loss in rolling bearings lubricated with wind turbine gear oils.•Comparison between numerical predictions and experimental results.•Adjustment of the lubricant dependent friction constants in the model.
As a part of the main research project within the aim of increasing significantly drive axle efficiency, this work focuses on rolling bearing friction torque lubricated with five fully formulated ...axle gear oils with different viscosity and different formulations. The lubricant tribological behaviour in different rolling bearings was analyzed. A modified Four-Ball Machine was used to test the rolling bearings. The effect of speed, temperature and axial load on rolling bearing friction torque was assessed. Experimental results for the internal friction torque were validated with an SKF model. Direct comparisons in terms of friction torque between axle gear oils when they are lubricating different rolling bearing types are presented and discussed.
•Five axle gear oils were selected. Their physical and chemical properties were presented.•Friction torque losses of thrust ball bearing, cylindrical roller thrust bearing and tapered roller bearing were measured.•Tests were performed in modified Four-Ball machine under a speed range from 75 rpm to 1200 rpm.•Friction torque is presented for high load (7 kN) at constant temperature (70 °C).•Boundary and full-film coefficient of friction for each rolling bearing and oil formulation were determined and validated.
Planetary gearboxes used in wind turbines very often have premature bearing and gear failures, some of them related to the lubricants used. Five fully formulated windmill gear oils with the same ...viscosity grade and different formulations were selected and characterized. The lubricant tribological behavior in a cylindrical roller thrust bearing was analyzed. A modified four-ball machine was used to assemble the bearings. They were submitted to an axial load and the tests were performed at velocities ranging between 150 and 1500rpm. Experimental results for the operating temperatures and for the internal friction torque are presented.
► Wind turbine gear oils with the same viscosity and different formulations. ► Density, dynamic and kinematic viscosities were measured. ► Frictional behavior of a cylindrical roller thrust bearing using a modified four-ball machine. ► The tests were performed at velocities ranging between 150 and 1500 rpm. ► Experimental results for the internal friction torque are presented.
FZG type A spur gears, lubricated with axle gear oils with high EP properties, were tested in an FZG back-to-back test rig, and their torque loss was measured for wide ranges of the input torque and ...speed.
Several models of the load-independent and load-dependent losses of the gearbox components (gears, rolling bearings and seals), were combined into a global power loss model for the prediction of the gearbox efficiency.
The average friction coefficient of the meshing gears was derived from the experimental results. A satisfactory correlation between experimental power loss measurements and the generated simulation results is observed under different operating conditions. Several aspects are discussed such as gear loss factor, friction coefficient and the influence of oil formulations.
•Power loss in rolling bearings lubricated with axle gear oils.•Power loss in gears lubricated with axle gear oils in FZG test rig.•Gear loss factor calculation.•Coefficient of friction between gear teeth for axle gear oils.•Comparison between experimental results and numerical predictions.
A 850kW wind turbine gearbox, widely used in wind farms, was used to perform efficiency tests of different wind turbine gear oil formulations.
One mineral and three polyalpholephin commercially ...available lubricants were chosen, all them are ISO VG 320 wind turbine gear oils.
Study the influence of different gear oil technologies in the overall gearbox transmission efficiency is the main objective of this work.
The results show that different energetic efficiency and different oil particle counting were obtained even when the same base oil is used.
•One mineral and three polyalpholephin ISO VG 320 wind turbine gear oils were chosen.•A 850kW wind turbine gearbox was considered to perform efficiency tests.•Different oil formulations, even with the same base oil, promote different energetic efficiency.•Different oil formulations promote lower particle counting through oil analysis.
Five fully formulated wind turbine gear oils were characterised. The gear oils have 320 ISO VG grade and different formulations: ester, mineral, PAO, PAG and mineral+PAMA.
A back-to-back FZG test ...machine, with re-circulating power, was used and a torque-cell was included on the test rig in order to measure the torque loss. Eight thermocouples were included to monitor the temperatures in different locations of the test rig.
Tests at 1.13, 2.26 and 6.79m/s were performed for different FZG load stages: K1, K5, K7 and K9. Both gearboxes were jet-lubricated with an oil flow of 3l/min. The input flow temperature was kept almost constant (80 ±1°C).
Friction generated between the meshing teeth, shaft seals and rolling bearing losses was predicted.
•Five wind turbine gear oils were selected. Density and viscosities were measured.•A back-to-back FZG machine was used and a torque cell included to measure the torque loss.•Torque loss was measured for a type C40 FZG gears.•Tests at 1.13, 2.26 and 6.79 m/s were performed at K1, K5, K7 and K9 load stages.•A torque loss model was developed and validated.
Planetary gearboxes used in wind turbines very often have premature bearing and gear failures, some of them related to the lubricants used. Five fully formulated wind turbine gear oils with the same ...viscosity grade and different formulations were selected and their physical characterization was performed. The lubricant tribological behaviour in a thrust ball bearing was analyzed. A modified Four-Ball Machine was used to assemble the bearings. They were submitted to an axial load and the tests were performed at velocities ranging between 150 and 1500rpm. Experimental results for the operating temperatures and for the internal friction torque are presented.
► Five wind turbine gear oils were selected. Density and viscosities were measured. ► Frictional behaviour of a thrust ball bearing (51107). ► A modified Four-Ball Machine was used and tests were performed between 150 and 1500rpm. ► Operating temperatures and internal friction torque, power loss and heat evacuated are presented. ► Rolling and sliding friction torques were determined.
This study was designed to investigate the influence of oil temperature and contact pressure on the tribological performance of three industrial gear oils but also on the corresponding changes taking ...place beneath the metal surfaces in contact. The result shows that increase in the oil temperature and contact pressure increases surface–additive interaction, promoting the formation of low-friction tribofilms. Subsurface characterisation of the worn surfaces shows that higher oil temperature and contact pressure promotes surface hardening of spheroidised AISI 52100 steel, degradation of the near-surface (< 0.8 µm) microstructural integrity and corresponds to an increase in wear. This study clearly shows that the gear oil formulations and the tribofilms they form uniquely influence the extent of subsurface deformation and wear.
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