CFD Predictions of Resistance and Propulsion for the JAPAN Bulk Carrier (JBC) with and without an Energy Saving Device

Abstract

Resistance and propulsion predictions for a ship is one of the most important tasks at the design stage in order to ensure that the ship can sail at a desired speed with the installed engine capacity and fulfill the mandatory regulations imposed by IMO such as Energy Efficiency Design Index (EEDI). Since new concerns on environment and efficiency have risen, predictions are getting more important and as a result the interests on Energy Saving Device (ESD) increased significantly. Traditional prediction tools can provide reliable results for resistance and propulsion but it is time-consuming, expensive and most importantly, scaling problems cannot be eliminated. Since Reynolds similarity is not fulfilled at model test, flow characteristics in experiments differ significantly from full scale. On the other hand, Computational Fluid Dynamics (CFD) solves this problem by offering both model and full scale results with a great detail of flow fields. Nevertheless accuracy of CFD is still limited and accuracy obtained from computations is always a concern. In this thesis, resistance, sinkage & trim, self-propulsion characteristics and local flow around the stern are predicted for the new test case JAPAN Bulk Carrier (JBC) for the Japan 2015 Workshop on CFD in Ship Hydrodynamics. Local flow is examined through mean velocity components, turbulent kinetic energy and Q-criterion at the stern region. Also, a comprehensive study is performed for revealing the best settings and procedures for POW tests and self propulsion tests using SHIPFLOW code. Free surface wave elevation, sinkage & trim are computed with the potential flow solver, viscous flow is evaluated by the Reynolds Averaged Navier-Stokes (RANS) solver. Propeller simulation is calculated through lifting line based propeller analysis module (LL) of SHIPFLOW. Additionally, a Verification and Validation (V&V) procedure is applied to the resistance, POW and self-propulsion results in order to assess the uncertainties and numerical errors.