Computation of Bowthrusters with RANS-Solver FreSCo

摘要

The results presented above give an interesting insight on the different effects causing the crossforce on the ship. But they have to be interpreted carefully since other effects, such as the interaction between the flow and the propeller are not modelled. In the above diagrams the power is the power used to accalerate the water. In reality the power that is applied to the thruster engine is of importance and therefore the propeller efficiency has to be considered. Taking into account that the propeller efficiency will increase with the homogenity of the wakefield, the round shape might provide a higher crossforce compared to the conical shape. The sharp edged shape on the other hand will perform worse in the comparrison of the crossforces. The results show that even if the calculated cross-forces do not differ significantly, the composition of the crossforce does. The applied bodyforce is equivalent to an applied pressure difference. Figures 5 and 6 show that the sharp edged geometry needs a much bigger bodyforce to reach the same crossforce than the other geometries, thus building up a higher pressure difference. In reality this will result in a higher pressure load on the propeller blades.