Drillship Moonpool Design to Reduce Added Resistance for Fuel Saving

摘要

During transit, a drillship moonpool creates added resistance that can be more than 50% of the totalrnresistance and hence significantly increase the fuel consumption. This paper reports a real case study forrnreducing moonpool added resistance by model tests and Computational Fluid Dynamics (CFD) simulations.rnModel test data show that, unlike conventional ships that experience nearly constant resistance, arndrillship resistance presents largely fluctuating behaviour. In CFD validation, the physics based CFD bestrnpractices are applied for resistance predictions. The largely fluctuating resistance is well captured inrnsimulations. It is found from flow visualizations of the large amount of CFD simulation results that thernhigh moonpool induced added resistance is mainly attributed to the vortices shed from the moonpool frontrnwall, which enter into the moonpool and impinge on the rear wall. The CFD predicted mean resistancernare in good agreement with the model test data, within 3% difference for a wide range of speeds. The wellrnvalidated CFD tool is applied to study the effects of moonpool dimensions on the added resistance. Thernresults of parametric study reveal a design principle that smaller moonpool dimension results in smallerrnadded resistance. Through comprehensive CFD parametric study, a universal design principle and CFDrnbest practice are established for industry applications.