Wind turbine main-bearing lubrication  – Part 1: An introductory review of  elastohydrodynamic lubrication theory

Hart, Edward; Mello, Elisha de; Dwyer-Joyce, R. S.

doi:10.5194/wes-7-1021-2022

Cited by 8 publications

(44 citation statements)

References 91 publications

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“…In order to study lubrication in the case of a wind turbine main bearing, an extensive contact conditions dataset, including roller loads, shaft speeds and contact dimensions (along with other relevant quantities), was generated. These values, combined with lubricant data and additional bearing information, allow film estimation formulas and EHL results to be applied (Hart et al, 2022). The process by which this dataset was generated will be detailed first, followed by a summary of bearing and lubricant information relevant to the study.…”

Section: Methodsmentioning

confidence: 99%

“…da/dt and db/dt. These values are important for determining whether non-steady EHL effects may be significant here (Hart et al, 2022). Roller trajectories from one time step to the next were evaluated assuming pure rolling.…”

Section: Generating the Contact Conditions Datasetmentioning

confidence: 99%

“…As described in Hart et al (2022), lubrication analysis requires information relating to bearing geometry, surface roughness and lubricant properties. The modelled bearing is an SKF 240/630CA/W33, which is used for wind turbines of the size being simulated in this work.…”

Section: Main-bearing and Lubricant Datamentioning

confidence: 99%

“…As such, simplified lubrication equations and associated results must be accompanied by a careful consideration of their context and validity. To this end, Part 1 of the present study (Hart et al, 2022) provides a detailed introductory review of EHL theory which seeks to provide an accessible and representative overview of the field. This paper, Part 2, details the main-bearing lubrication analysis itself, including simulations and dataset generation, internal load and contactpatch evaluation, lubrication conditions, and film thickness analyses.…”

Section: Introductionmentioning

confidence: 99%

“…A thorough treatment of relevant EHL theory has been provided in Part 1 of this study (Hart et al, 2022). As such, familiarity with the material presented there is assumed throughout this paper.…”

Section: Introductionmentioning

confidence: 99%

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Wind turbine main-bearing lubrication – Part 2: Simulation-based results for a double-row spherical roller main bearing in a 1.5 MW wind turbine

2022

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Abstract. This paper is the second in a two-part study on lubrication in wind turbine main bearings. Where Part 1 provided an introductory review of elastohydrodynamic lubrication theory, this paper will apply those ideas to investigate lubrication in the double-row spherical roller main bearing of a 1.5 MW wind turbine. Lubrication is investigated across a “contact conditions dataset” generated by inputting main-bearing applied loads, estimated from hub loads generated using aeroelastic simulation software, into a Hertzian contact model of the main bearing. From the Hertzian model is extracted values of roller load and contact patch dimensions, along with the time rate of change of contact patch dimensions. Also included in the dataset are additional environmental and operational variable values (e.g. wind speeds and shaft rotational speeds). A suitable formula for estimating film thickness within this particular bearing is then identified. Using lubricant properties of a commercially available wind turbine grease, specifically marketed for use in main bearings, an analysis of film thickness across the generated dataset is undertaken. The analysis includes consideration of effects relating to temperature, starvation, grease thickener interactions and possible non-steady effects. Results show that the studied main bearing is at risk of operating under mixed lubrication conditions for a non-negligible proportion of its operational life, indicating that further work is required to better understand lubrication in this context and implications for main-bearing damage and operational lifetimes. Key sensitivities and uncertainties within the analysis are discussed, along with recommendations for future work.

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Section: Methodsmentioning

confidence: 99%

Section: Generating the Contact Conditions Datasetmentioning

confidence: 99%

Section: Main-bearing and Lubricant Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Wind turbine main-bearing lubrication – Part 2: Simulation-based results for a double-row spherical roller main bearing in a 1.5 MW wind turbine

2022

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Wind turbine main bearing rating lives as determined by IEC 61400‐1 and ISO 281: A critical review and exploratory case study

Kenworthy,

Hart,

Stirling

et al. 2023

Wind Energy

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This paper studies the rating lives of wind turbine main bearings, as determined by the IEC 61400‐1 and ISO 281 standards. A critical review of relevant bearing life theory and turbine design requirements is provided, including discussion on possible shortcomings such as the existence (or not) of the bearing fatigue load limit and the validity of assuming linear damage accumulation. A detailed exploratory case study is then undertaken to determine rating lives for two models of main bearing in a 1.5 MW wind turbine. Rating life assessment is carried out under different conditions, including various combinations of main bearing temperature, wind field characteristics, lubricant viscosity, and contamination levels. Rating lives are found to be sufficiently above the desired 20‐year design life for both bearing models under expected operating conditions. For the larger bearing, operational loads are shown to be below or close to the bearing fatigue load limit a vast majority of the time. Key sensitivities for rating life values are temperature and contamination. Overall, the results of this study suggest that an ISO 281 rating life assessment does not account for reported rates of main bearing failures in 1 to 3 MW wind turbines. It is recommended that a similar analysis be undertaken for ISO/TS 16281 rating lives, along with further efforts to identify principal root causes of main bearing failures in future work, possibly leading to a new application standard specific to this component. It is also recommended that the impacts of partial wake impingement on main bearing rating lives are investigated.

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Dynamische Modellierung von Schlupf bei Windturbinen Pendelrollen-Hauptlager

Mello

Hart

Guo

et al. 2023

Forsch Ingenieurwes

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This paper considers the problem of the dynamic modelling of macro slip in spherical roller bearings. By revisiting the fundamental physics which drive these systems, potential issues in existing models have been identified. Furthermore, in pure rolling conditions it was found that governing differential equations become "stiff", requiring the use of implicit methods of time integration. The problem of individual roller macro slip in a wind turbine main bearing is then investigated using a simplified representation of system dynamics. Model results indicate clear links between slip/friction and the operational strategy of the wind turbine, as well as significantly higher frictional effects in the downwind main bearing row. Due to modelling simplifications, these results should not yet be considered conclusive, with further work required. Dynamische Modellierung vonSchlupf bei Windturbinen Pendelrollen-Hauptlager Zusammenfassung Dieser Beitrag befasst sich mit dem Problem der Dynamischen Modellierung des Makroschlupfs in Pendelrollenlagern. Durch eine Überprüfung der grundlegenden physikalischen Zusammenhänge, die diese Systeme antreiben, wurden potenzielle Probleme in bestehenden Modellen identifiziert. Darüber hinaus wurde festgestellt, dass die maßgeblichen Differentialgleichungen unter reinen Rollbedingungen "steif" werden, was den Einsatz impliziter Methoden der Zeitintegration erfordert. Das Problem des Makroschlupfes einzelner Rollen in einem Hauptlager einer Windturbine wird dann anhand einer vereinfachten Darstellung der Systemdynamik untersucht. Die Modellergebnisse zeigen klare Zusammenhänge zwischen Schlupf/Reibung und der Betriebsstrategie der Windkraftanlage sowie deutlich höhere Reibungseffekte in der windabgewandten Hauptlagerreihe. Aufgrund von Vereinfachungen der Modellierung sollten diese Ergebnisse noch nicht als abschließend betrachtet werden; weitere Arbeiten sind erforderlich.

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Wind turbine main-bearing lubrication – Part 1: An introductory review of elastohydrodynamic lubrication theory

Cited by 8 publications

References 91 publications

Wind turbine main-bearing lubrication – Part 2: Simulation-based results for a double-row spherical roller main bearing in a 1.5 MW wind turbine

Wind turbine main-bearing lubrication – Part 2: Simulation-based results for a double-row spherical roller main bearing in a 1.5 MW wind turbine

Wind turbine main bearing rating lives as determined by IEC 61400‐1 and ISO 281: A critical review and exploratory case study

Dynamische Modellierung von Schlupf bei Windturbinen Pendelrollen-Hauptlager

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