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Abstract:This study examined the effects of wind loads on a floating production storage and offloading (FPSO) vessel, focusing in particular on the impact of the turbulent wind profiles, the level of details of the topside structures, and the operation modes of the gantry cranes. A series of wind tunnel tests were performed on the FPSO vessel model, developed with a scale of 1:200. It was observed that the wind loads measured using a low-detail model were often greater than those measured using a high-detail model. The measured wind loads corresponding to the Norwegian Maritime Directorate (NMD) profile with an exponent of 0.14, were approximately 19% greater than those corresponding to the Frøya profile in the entire range of wind directions, because of the slightly higher mean wind speeds of the NMD profile. The wind forces increased by up to 8.6% when the cranes were at operating mode compared to when they were at parking mode. In view of the observations made regarding the detail level of the tested models, a medium-level detail FPSO model can be considered adequate for the wind tunnel testing if a high-detail model is not available.Keywords: FPSO vessel; wind tunnel test; aerodynamic force; boundary layer profile; wind load
with ρ0 being a reference air density, and ζ representing the resistance coefficient. Each component exhibits a particular resistance coefficient and refers to a characteristic flow speed (Idelchik 1966; VDI-Gesellschaft Verfahrenstechnik und Chemieingenieurwesen 1998). The characteristic flow speed can be expressed in terms of the outlet velocity of the wind tunnel. Adding all pressure losses, a velocity-dependent pressure drop curve is found.
where ui represents one of the n actually measured velocity values at the current position. The turbulence intensity is presented in Fig. 8 for all three planes and for 0 inclination. The readings of the mixing layer at the edge of the free jet have been omitted since they do not represent the flow in the test section. Inside the flow region, the turbulence intensity is approximately 1% at the exit cross section and up to 2% at the end of the test section, which appears to be acceptable, though these are rather high values compared to wind tunnels specially designated for aerodynamic research. To reduce the turbulence level additional wire screens with finer meshes would have to be implemented, though with these additional flow resistances the required flow velocity could presumably not be achieved with the installed fans. For that reason, the turbulence level has been accepted as it is. 153554b96e