The design of a well performing pre-swirl stator (PSS) should strictly account for
the full scale flow environment as met individually by each stator fin. In the European GRIP
project an actual design has been delivered for a bulk carrier and was installed for trials. The
results of the speed/power measurements could be compared to the trial data obtained 2 weeks
earlier, when the stator was not mounted. The power gain with mounted stator was
considerable. As the design was adapted to a computed full scale flow environment, the
question arises whether such results could have been predicted prior by model tests performed with
geometrical similar stator and propeller. For this purpose we analysed the model
propulsion mode numerically. In summary the model scale analysis revealed considerable
differences to the full scale setup, if the performance of the fins is compared
individually. However in this numerical assessment of scale effects the overall decrease
of power at the propeller showed only minor changes between model and full scale.
The second question coming up after the trials have been completed addresses the propeller and its
drop in RPM, an expected and forecasted result. Such an RPM change in itself will have a positive
effect on the required power due to a reduction of viscous effects on torque. On the other hand due
to requirements from the engine side it will usually be necessary to adapt the propeller geometry
and compensate the RPM drop. It is investigated numerically, to
what extent the required power will increase for such an RPM adapted propeller
