SMP – Numerical analysis of rudder effects upon ducted propeller units

It is a well known fact that the use of ducted propellers is a good option for those applications that need high thrust values at low speed. Because of its particular working conditions this is the case of trawlers which velocities when trawling are between 3 and 5 kts. Beyond this, it is of particular interest the effect that steering elements have on two aspects; the effect upon propulsive factors and the manoeuvrability capability.

In the present paper a study of the effects upon propulsive factors and the manoeuvrability by different rudder configurations and shapes have been carried out. There are several options; nozzle-propeller rudder, three rudder arrangements, one rudder arrangements, flow adapted rudders, etc.

The calculations have been carried out in two different phases; in the first one the calculations were carried out in an uniform flow field for the complete system: ducted propeller- rudder/rudders. And for the second one a typical trawler wake field was employed. For both phases the effect of the rudder on the energy efficiency and also the manoeuvrability capabilities of each system were studied. All the calculations have been carried out using commercial CFD code STAR-CCM+.