Effect of the transition piece on the natural frequencies of monopile-supported offshore wind turbines
Year: 2024
Type: article
Abstract: The lateral natural frequency of an offshore wind turbine (OWT) is a crucial factor to consider in the design of OWT foundations. Eighty percent of currently installed OWTs are mounted on monopile (MP) foundations, which are connected to the superstructure via a transition piece (TP). To explore the differences in natural frequencies between grouted connection (GC) and TP-less designs, this study incorporates a transition piece into the calculation model of the OWT system. The variable cross-sectional characteristics of the tower and pile‒soil interaction are considered. Based on the Timoshenko beam theory and transfer matrix method, the characteristic equations of the lateral natural frequency of the OWT are derived to analyze the sensitivity of the natural frequency to structural parameters. The results indicate that the height of the OWT system has the most significant impact on the natural frequency. For the NREL-5MW wind turbine, the TP-less design reduces the first natural frequency of the OWT by 1.41% and elevates the second and third natural frequencies by 11.89% and 2.72%, respectively, compared to the grouted connection design. As the structural parameters of the OWT system vary, the discrepancy between the natural frequencies obtained from the GC and TP-less design approaches also evolves.
Authors: Hengkai Niu, Zhendong Shan, Lvjun Tang, Ziquan Wang
Language: English
Topic: Wave and Wind Energy Systems
Subfield: Ocean Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,790
Awards: G1305724988, G3432031421
OpenAlex ID: W4402859498