Pusher-barge system with different maneuvering and propulsion devices were modeled and analyzed. Both azimuth thrusters and conventional propulsion system (which is composed by rudder and propeller) were considered in the pusher. An additional azimuth thruster installed on the bow of the barges was also analyzed, in order to increase the maneuverability of the convoy.
Hydrodynamic derivatives for different pusher-barge configurations used in Tietê-Paraná river (B × L = 2 × 3, 1 × 2 and 1 × 1) were obtained from previously published works and complemented by captive model tests and CFD calculation executed in the context of the present project, presented in a complementary paper in this conference Grassi et al. (2013). Numerical models for each propulsion and maneuvering devices were obtained by standard formulations. A time-domain simulator was then implemented and the standard zig-zag and turning circle tests were simulated to compare performance of the different maneuvering and propulsion devices.
It was verified that pushers equipped with azimuth thrusters can increase the maneuverability of the system for slow speed navigation. For higher speeds, the conventional rudder and propeller pusher presents similar or even better maneuvering properties, since the effectiveness of the rudder increases.
The additional bow azimuth thruster can also improve maneuverability parameters, since the force applied at the bow increases the turning moment. However, its efficiency depends also on the speed and the instantaneous pivot-point of pusher-barge system. A broad discussion about the advantages and physical limitations of this additional bow azimuth thruster is presented.