Wind Shielding Effects on DP System of a Shuttle Tanker

Abstract

The effects of hydrodynamic and aerodynamic interactions on a typical shuttle tanker (ST), when offloading a FPSO moored in Spread Mooring System (SMS) configuration are being studied in an extensive research project conducted at the University of Sa˜o Paulo, in collaboration with Petrobras. The numerical models will be incorporated in the simulators in order to evaluate the impact of such effects on the dynamics of the ST and on its DP System power requirement. Present paper focuses the wind shielding effect, since current and wave wake effects were already treated in previous works (Illuminatti et al., 2009; Queiroz Filho et al., 2009). A detailed CFD model of the FPSO and ST were used to evaluate the horizontal forces and yaw moment induced in the ST by the wind when inside the shadow zone defined by the FPSO. The CFD model was calibrated using wind tunnel measurements of a similar system. Typical tandem configurations were considered for the connection and oil-transfer stages of the operation. The power requirements for each DP thruster were then calculated, considering a thrust allocation algorithm. The comparisons with the stand-alone ST configuration indicated that the wind shielding effect is important concerning DP power. Besides, it is proposed a simplified model for wind forces and moment in the ST, considering the wind velocity field in the wake of the FPSO (CFD calculation). The procedure is based on report [7] where the wind force is evaluated through de summation of forces and moment in the stern, middle and bow parts of the ST. Such procedure has the advantage of requiring only one CFD calculation (for obtaining the velocity field downstream FPSO).

Experimental study of aerodynamic loads on an LNG carrier and floating platform

“…A recent study by Tannuri et al [13] has also looked at the effect of wind and the interaction effect between a platform and a shuttle tanker but they considered a tandem situation instead of the side-by-side case considered in this study.…”

Wind Effect Estimation and Navigational Effect in Side by Side Offloading Operation for FLNG and LNG Carrier Ships

“…Here, 1 a , 2 a are decided as 0.69 and 0.20 respectively to fit the experimental trend. The calculated results using Eq.14 are presented in Figure 11 with the experimental results.…”

“…The authors have focused on the wind shielding effect in side by side offloading situation of operating ships in this paper. In the past presented papers by another authors [1]~ [4], general information noted the importance of consideration for the wind shielding effect was pointed out, and in some cases, CFD (Computational Fluid Dynamics) calculations in the ship shielding conditions had conducted [4]. Detail analysis of the effect based on experimental or the wind shielding effect on calculated results, however, have not generally presented in them.…”