Powering Performance
Predicting the Powering Performance in terms of power and propeller speed remains one of the three major spearheads of the Resistance and Propulsion programme. The application of CFD tools and research to improve full scale measurements are prominently on the agenda. The focus on quality of predictions becomes also apparent from efforts to determine the uncertainty in speed-power predictions on both model scale as well as for full scale and from computations. With the tendency in both the research area as well as in the industry to compare the results from experiments, full scale and computations, it becomes ever more important to know the uncertainty for each prediction.

Predict and verify the powering performance of all floating vessels and bodies with the requested accuracy. For ships power and propeller rotation rate need to be predicted from an optimal combination of CFD and model tests with a known low uncertainty.

State of the art
It has been demonstrated that CFD can give improved quantitative predictions of scale effects, such as on the form factor (used for the prediction of full scale viscous resistance) and the wake fraction (used to couple the open water propeller characteristics to the power demand by the hull). Another way to determine the full-scale power prediction is by the sole use of CFD.
The initiation of JIP projects on ship performance have resulted in a good network with the shipping industry (Vessel Operator Forum) and have lead to the acceptance of a MARIN proposed Trial procedure by ITTC and IMO. Negotiations are ongoing with ISO to have these procedures being accepted on a wider scale.

Vision 2016
To determine, using an optimal combination of CFD and model test data, a speed-power prediction for single screw ships with a higher accuracy and at lower costs than the current predictions based on model tests and to measure, at full scale, the speed-power performance of ships with at most 2% uncertainty.

Vision 2020
Determine the powering performance , using an optimal combination of CFD and model test data, (including cavitation, ventilation, engine loads and bearing loads) for a broad range of ships in off-design conditions, including seakeeping and manoeuvring aspects (added resistance, steering effects).

In the context of this research programme, MARIN is, or has been, working on the following JIPs:

Example applications
  • Prediction of power-speed at full scale with known uncertainty for example using a combination of complex model tests and CFD for windmill-installation vessels.
  • Full scale validation of speed-power performance e.g. for EEDI validation.
  • Provide a more detailed analysis of efficiencies and resistance for further design improvement.
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