Flexcom > Examples > L - Wind Energy > L04 - IEA 15MW RWT > Results

Introduction

A subset of IEC design load case conditions was selected by UMaine to gauge the performance of the reference semisub in normal and extreme design conditions which are representative of the U.S. East Coast. The floating offshore wind turbine’s performance under these design conditons is summarised via statistics for various outputs, including platform motion, mooring line tension, tower base moment, nacelle acceleration etc.

The published report on the UMaine semisub presents overall DLC results in graph form only. The underlying data is not supplied which makes comparisons between UMaine and Flexcom difficult. However a visual inspection of the published report suggests that the Flexcom results show reasonable agreement with the published data. It should be note that for efficiency reasons, the Flexcom simulations considered only one value of wind and wave seed while the UMaine simulations typically considered 6 seeds. The following figures allow some comparisons to be made between the published report (Allen et al., 2020) and Flexcom simulation results. Note that the DLC1.4 results for Flexcom are set to zero as this load case has not yet been included in the example.

Design load cases are analysed in Flexcom using simulations of 10-minute (600 second) duration. An additional 5-minutes (300 seconds) is included at the beginning to accommodate initial transients. For each seastate, a screening test is performed in advance of the main simulation, from which the peak wave occurring over a 3-hour storm is identified and noted. The start time for each design simulation is set equal to the peak wave time minus 5 minutes. This ensures that the largest wave for each wind condition is experienced by the system. Further information on this aspect is presented in Wave Peak Times.

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