Full scale performance of propellers is still an area of large uncertainty during the propeller design phase, during the extrapolation of model tests for powering predictions and during full scale monitoring. On full scale, propellers usually operate with turbulent flow. On model scale, however, laminar flow, flow transition and more pronounced flow separation are encountered. Model tests and powering predictions suffer from these effects.

It is proposed to perform new open-water model tests using turbulators such that the boundary layer would be tripped towards a turbulent flow. Turbulators on the leading edge of the model scale propellers are very efficient in tripping the boundary layer. The turbulent flow on the propellers at model scale reduces the scale effect uncertainties. New scale corrections need to be applied, thereby replacing ITTC corrections that did not capture the scale effects correctly. The corresponding uncertainty of the final prediction and the standard deviation to full scale trials would greatly improve.

The Reynolds scale effects for a fully turbulent flow can be computed with CFD. MARIN is confident that using RANS computations, reliable scale corrections can be obtained for tripped propellers. These computations have become mature, reliable and robust, and are suited to this task.