Applicability study of rules for wind load calculation of FPSO based on CFD

Objective  At present, the oil companies international marine forum (OCIMF) rules are frequently used to calculate wind load for large tankers and the American petroleum institute (API) rules for offshore platforms. However, due to the complexity of floating production storage and offloading (FPSO) superstructures, whether these two sets of rules can be applied to the wind load calculation of FPSO requires further study.

Methods This paper establishes a numerical model of a 300 000-ton class FPSO with a universal superstructure. The wind load on the FPSO under severe sea conditions and different wind angles is calculated and compared to the results of the rules. The shielding effect and heeling angle of the FPSO are analyzed.

Results The maximum heeling moment and wind load under an upright floating attitude appear at a 270° wind angle. The heeling moment and wind load under a heeling floating attitude are greater than those under an upright floating attitude, and the maximum heeling moment appears at a 10.5° heeling angle and a 280° wind angle. The results of the API and OCIMF rules show big differences compared with CFD: the differences between their results at a 270° wind angle and CFD are 13.6% and 24.5% respectively.

Conclusion  The flow field details obtained by numerical simulation are conducive to analyzing the shielding effect between superstructures and enhancing the accuracy of ship wind load prediction, thereby providing valuable references for the stability design of FPSO.