Simulative investigation of plain bearing main bearing units for wind turbines in the 5MW class

Abstract

[ES] La cátedra de accionamientos de Energía Eólica investiga el comportamiento de los trenes de accionamiento de las modernas multimegaváticas turbinas eólicas (WT, en inglés Wind Turbines). Los objetivos de la investigación son aumentar la disponibilidad, la robustez y la eficiencia energética de los aerogeneradores y reducir el coste nivelado de la electricidad. Para ello, se utilizan combinadamente herramientas de desarrollo de software y plataformas de pruebas de sistemas modernos.

Las turbinas eólicas (WT) actuales utilizan exclusivamente rodamientos de rodillos como cojinetes principales. Sin embargo, cuando ocurren daños, estos generan altos costes de reparación. Por este motivo, se está investigando el uso de cojinetes lisos como cojinete principal de los aerogeneradores. Entre otras cosas, estos permiten el reemplazo de segmentos de rodamientos individuales, lo que reduce significativamente los costes de reparación en caso de daños. Por lo tanto, en el CWD (Center for Wind Power Drives), se desarrollará una unidad de cojinete principal con cojinetes lisos en una escala relevante (5 MW).

Por lo tanto, el objetivo de este trabajo es investigar unidades de cojinetes principales con cojinetes lisos mediante simulaciones EHD. Se deben simular diferentes geometrías de rodamientos y examinar su idoneidad.

[EN] Wind power has emerged as a significant and rapidly growing source of renewable energy worldwide. As the demand for clean and sustainable energy continues to increase, the efficient and reliable operation of wind turbines becomes paramount. However, one critical component that often experiences premature failure is the main bearing of wind turbines, which can have failure rates of up to 30%. The high repair costs associated with roller bearings used in wind turbine main bearings pose a significant challenge for the wind energy industry. These costs not only include the actual repair expenses but also the downtime required for the repairs, which can lead to substantial financial losses. It is imperative to explore alternative solutions that can minimize repair costs and reduce downtime. One potential solution that has gained attention is the use of segmented plain bearings, such as the innovative FlexPad design. The FlexPad design offers the advantage of easy exchangeability of its sliding segments, allowing for on-tower repair without the need to dismount the entire rotor. This convenience can potentially save significant time and resources. However, during the transfer of the FlexPad design to wind turbines with power ratings exceeding 5 MW, a challenge surfaced. The larger turbines needed stiffer sliding segments in order to handle the increased loads and forces generated by the larger size of the turbines. This would result in thicker sliding segments and an increase in weight, presenting a new obstacle to easy serviceability and restricts one of the key advantages of plain bearings. Therefore, in order to address this issue and maintain the convenience and efficiency offered by the FlexPad design, it is crucial to explore and understand the influence of sliding segment design on the hydrodynamic load bearing capacity. To achieve this objective, a simulative investigation using elastohydrodynamic (EHD) simulations was employed to explore various bearing geometries and assess their performance. This research will specifically focus on studying the relationship between sliding segment design, its deformation under load, and the resulting hydrodynamic pressure build up. By comprehensively analyzing these factors, it will be possible to ascertain whether segment weight can be minimized without compromising the overall performance of the bearing. In conclusion, the findings of this study will contribute valuable insights into the optimization of the FlexPad bearing design for wind turbines. The ultimate goal is to gain deeper insights into the FlexPads sliding segment design and its relationship to the FlexPad’s hydrodynamic performance