Wear in wind turbine pitch bearings—A comparative design study

Abstract

We tested two types of ball bearings with an outer diameter of 750 mm to learn more about the challenges of oscillating motions for pitch bearings. The experimental conditions are derived from aero‐elastic simulations, long‐term wind speed measurements and a scaling method that considers loads and pitch angles. As a result, the parameters relevant for pitch bearings are represented appropriately, and the findings are transferable to other bearing sizes. For the tested parameter sets, severe wear occurred for over 90% of the exposed contact areas after 12 500 oscillating cycles. Decreasing the number of cycles to 1250 leads to a mix of exposed areas with 13% severe wear, 32% mild wear and 55% no wear, with no apparent pattern. The results demonstrate that a comparatively small amount of consecutive cycles can lead to severe wear. A new type of bearing tested showed less wear for the selected operating conditions.

Exploring Limiting Factors of Wear in Pitch Bearings of Wind Turbines with Real Scale Tests

“…Schwack et al also tested two bearing types with an outer diameter of 750 mm and a contact pressure of 2.0 GPa. They differed between two x/2b ratios (2.67 and 11.44) and were able to create wear for both bearings and for both x/2b values (Schwack et al, 2021). So far, all test bearings have a diameter lower than one meter.…”

“…There are many publications regarding wear in rolling bearings. To the knowledge of the authors, only a few of them refer explicitly to blade bearing application and include tests with bearings to increase the knowledge about the relation between operation parameters of a wind turbine and wear (Becker, 2012;Schwack et al, 2020;Wandel S., and Bartschat B., 2021;Schwack et al, 2021;Stammler, 2020). The authors use different bearing sizes and types according to the available test infrastructure.…”

Wear Development in Oscillating Rolling Element Bearings

“…However, the stochastic nature of the wind and operating conditions of the wind turbine as well as the influence of the specific order of occurrence of cyclic movements of the blade bearings makes rating the risk of wear damage a very difficult topic. Thus, there is a certain risk, that site specific wind conditions stay between cut in and rated wind speeds for long periods of time and IPC operation can add up over 13 000 cycles without significant change in the mean angle of oscillation [7]. This makes a better understanding of the wear mechanisms especially for a comparably low number of oscillation cycles valuable.…”

Rating of a Pitch Bearing for a 1.5-Megawatt Wind Turbine

“…Large-diameter pitch bearing tests have been conducted to determine friction torque (González et al 2008;Han et al 2015;Menck et al 2022) and fatigue lives and wear characteristics (Handreck et al 2015;Becker et al 2017;Grebe et al 2018;He et al 2018;Schwack, Prigge, and Poll 2018;Fischer and Mönnig 2019;Schwack et al 2020;Schwack et al 2021;Song and Karikari-Boateng 2021). Other assessments have been made of the turbine controller characteristics Menck, Stammler, and Schleich 2020;Stammler et al 2020) and stiffening plates (Loriemi et al 2020).…”