A code-to-code comparison for dynamic modelling and response analysis of offshore wind turbine blade mating process

Abstract

Offshore wind turbine blade installation using jack up crane vessel is a challenging task. Wave and wind induced loads on the installation system can cause large relative motion between the blade root and the hub during the mating process. Currently, several numerical tools are used to analyse such critical global motion responses; however, the industry suffers from lack of experiments and full-scale measurements to validate the accuracy of these results. Consequently, a code-to-code comparison exercise becomes critical as it allows comparing different numerical tools for reliable prediction and verification of results. In the present paper, a numerical model of the offshore wind turbine blade mating process using a jack-up crane vessel is developed in OrcaFlex, and a code-to-code comparison is performed against SIMA; both these tools are immensely used in the industry for modelling marine operations. Different comparisons are made between both the tools such as: (1) modal analyses of the jack-up vessel and the blade lifting gear, (2) time-domain analysis of the fully coupled installation vessel-crane-blade system, and (3) a comprehensive sensitivity study based on different seed numbers and simulation periods. The results of the study show a good agreement between both the tools with a deviation of less than 3% in terms of modal analysis and less than 5% variation in time domain results. Further, the paper provides modelling guidelines for the industry practitioners that heavily rely on both the tools for modelling marine operations.