The present work deals with the prediction of the horsepower and RPM of a tanker during sea trials by applying an in house CFD code. The code solves the steady RANS equations in calm water using the finite volume approach. A hybrid surface-tracking method is employed to calculate the free-surface and the propeller is modeled according to the actuator disk approximation. The main goal of the paper is to investigate the influence of the turbulent model on the acquired results. In this respect, two turbulence models are examined i.e. the standard k-ε and the k-ω-SST. The computed results at the speed of the sea trials are compared to the measured data at full displacement. Besides, a ballast condition is studied in order to explore the behavior of the two models in two quite different situations.

In the present work the resistance and the dynamic behavior of two series 60 models with block coefficient of 0.6 and 0.7, has been extensively tested in the towing tank of the Laboratory for Ship and Marine Hydrodynamics (LSMH) of the National Technical University of Athens (NTUA). The resistance tests concerned two loading conditions for a range of speed from 0.492 m/s to 1.912 m/s which corresponded to Froude Number of 0.089 to 0.356. Regular wave testing were conducted for two speeds (1.367 m/s and 1.804 m/s which corresponds to Fr of 0.25 and 0.33) and for nine frequencies with different altitude covering extreme realistic conditions. Results, referring to the resistance, the CG rise, the dynamic trim, the added resistance and the RAO coefficients are presented in detailed. Useful conclusions are drawn following the discussion of the experimental results.

The basic aim of this research was to compare the experimentally evaluated flow field at the stern region of a hull form with large block coefficient with the respective numerical results. To this end, a Five-Hole Pitot tube was used to capture the wake flow at the stern region of a scaled model of a bulk carrier in the towing tank of the Laboratory for Ship and Marine Hydrodynamic (LSMH) of the National Technical University of Athens (NTUA). The measurements were carried out at three aft sections of the model, where large scale vortices are usually generated: the section at the propeller, a section ahead of it and another one under the transom stern. The model was towed at a speed of 1.214 m/s, corresponding to Fn =0.17. The tube was calibrated on air at an equivalent Re, while a second in-house calibration technique was developed to consider installation misalignments and to increase overall measurement accuracy. The numerical calculation of the flow was performed using CFD tools developed at LSMH of NTUA. The method solves the RANS equations by applying the finite volume approach underneath a prescribed free surface which is derived by a potential flow code. The numerical results are in good agreement with the experimental ones, confirming the robustness of both methods.