TY - JOUR

T1 - A study of grease lubricants under wind turbine pitch bearing conditions

AU - Schwack, Fabian

AU - Bader, Norbert

AU - Leckner, Johan

AU - Demaille, Claire

AU - Poll, Gerhard

N1 - Funding information: The authors would like to thank the German Federal Ministry for Economy Affairs and Energy (BMWi) for funding the project Highly Accelerated Pitch Bearing Test (HAPT — Project number 0325918 ) from which this paper originated. The simulation results presented here were partially carried out on the cluster system at the Leibniz University of Hannover, Germany. Furthermore the authors would like to thank Felix Prigge , Sirin Gnadeberg , Artjom Byckov , Steffen Helmedag and Fabian Halmos for supporting the presented research. The authors would like to thank the German Federal Ministry for Economy Affairs and Energy (BMWi) for funding the project Highly Accelerated Pitch Bearing Test (HAPT ? Project number 0325918) from which this paper originated. The simulation results presented here were partially carried out on the cluster system at the Leibniz University of Hannover, Germany. Furthermore the authors would like to thank FELIX PRIGGE, SIRIN GNADEBERG, ARTJOM BYCKOV, STEFFEN HELMEDAG and FABIAN HALMOS for supporting the presented research. The research was partly funded by BMWI.

PY - 2020/8/15

Y1 - 2020/8/15

N2 - Pitch bearings in wind turbines are affected by reciprocating motion due to pitch control. The combination of oscillating operation, high loads, and mixed lubrication often leads to wear. Grease lubricants in wind turbine pitch bearings should be designed to avoid such wear. Due to different available grease lubricants, the anti-wear properties are investigated under downscaled wind turbine pitch bearing conditions. The downscaling is accomplished by load simulation for a pitch bearing and analysis of the pitch movements for a 7.5 MW reference turbine. The operational conditions of the four point contact ball bearing with 5 m outer diameter are scaled to angular contact ball bearings of the size 7208. The investigations are concluded with contact model experiments. Six Industrial grease lubricants for wind turbine pitch bearings are tested that follow very different compositions. The investigations reveal, that none of the tested grease lubricants was able to reduce wear for all tested conditions. After 250000 cycles certain conditions lead to severe wear. Therefore, the pitch controller should avoid such conditions if possible. Nevertheless, grease lubricants with low base oil viscosities and high bleeding rates are best on average for the tested conditions. Furthermore, the results of the bearing experiments are comparable to the model experiments.

AB - Pitch bearings in wind turbines are affected by reciprocating motion due to pitch control. The combination of oscillating operation, high loads, and mixed lubrication often leads to wear. Grease lubricants in wind turbine pitch bearings should be designed to avoid such wear. Due to different available grease lubricants, the anti-wear properties are investigated under downscaled wind turbine pitch bearing conditions. The downscaling is accomplished by load simulation for a pitch bearing and analysis of the pitch movements for a 7.5 MW reference turbine. The operational conditions of the four point contact ball bearing with 5 m outer diameter are scaled to angular contact ball bearings of the size 7208. The investigations are concluded with contact model experiments. Six Industrial grease lubricants for wind turbine pitch bearings are tested that follow very different compositions. The investigations reveal, that none of the tested grease lubricants was able to reduce wear for all tested conditions. After 250000 cycles certain conditions lead to severe wear. Therefore, the pitch controller should avoid such conditions if possible. Nevertheless, grease lubricants with low base oil viscosities and high bleeding rates are best on average for the tested conditions. Furthermore, the results of the bearing experiments are comparable to the model experiments.

KW - Blade bearing

KW - False brinelling

KW - Grease

KW - Pitch bearing

KW - Wear

KW - Wind energy

UR - http://www.scopus.com/inward/record.url?scp=85084851045&partnerID=8YFLogxK

U2 - 10.1016/j.wear.2020.203335

DO - 10.1016/j.wear.2020.203335

M3 - Article

AN - SCOPUS:85084851045

VL - 454-455

JO - Wear

JF - Wear

SN - 0043-1648

M1 - 203335

ER -