15 MB - Great Lakes Maritime Research Institute

1. IntroductionThe Ballast­Free Ship Concept has been recently invented [US Patent #6694908 2004] andinvestigated [Kotinis et al. 2004, Kotinis 2005, Ballast Water News 2004] at the University ofMichigan. Even though the feasibility of the concept was demonstrated, the aforementionedanalysis was limited by its required comprehensive research scope and associated budget. Thus,it was only feasible to support model testing that utilized an existing model. Although the vesseltype of greatest interest for the Great Lakes nonindigenous aquatic species introduction problemis the Seaway­sized bulk carrier, the best available model was of a relatively finer, higher­speedbarge­carrying Lighter Aboard Ship (LASH) vessel. This existing model was modified to utilizea more conventional stern, but the model test results were not directly applicable to the Seawaysizedbulk carriers studied in detail in the rest of the research effort.The current research focuses on the design of a typical Seaway­sized bulk carrier and theconstruction of a scaled model to be utilized in subsequent towing tank experiments. This modelhas already been procured and is expected to be delivered to the University of Michigan at theend of October, 2006.A major part of the initial hydrodynamic analysis that was performed on the modifiedLASH vessel was based on the ship­specific Computational Fluid Dynamics (CFD) codeSHIPFLOW ® [Flowtech Int. 1998], which has been shown to have significant limitationsregarding the prediction of the important viscous flow near the stern.In the current research, the external flow around the Ballast­Free bulk carrier has beeninvestigated numerically using FLUENT ® [Fluent 2005]. These external flow results have beenutilized to obtain the necessary boundary conditions for numerical simulation (also inFLUENT ® ) of the water flow in the longitudinal ballast trunks. The internal flow was simulatedin order to estimate the flow rate scaling factor needed in preparation for the subsequent towingtank experiments.In the next stage of this research, the model will be utilized for towing tank experiments inorder to study, in more detail, the hydrodynamic impact of the Ballast­Free Ship Concept. Theexperimental and numerical hydrodynamic investigation, combined with an optimizationprocedure, is expected to lead to a design solution that could offer a net savings in RequiredFreight Rate (RFR) relative to alternate ballast water treatment methods and approaches. Thenumerical solution will be refined and validated through the scale model testing.6