Sharif Digital Repository

Special geometrical sections, known as “duct”, which can be installed on merchant vessels stern in order to improve propulsion system and propeller performance, today have evolved considerably. The force which produces by the propeller depends on efficiency of propulsion system. In the way of improving the efficiency of propulsion systems, by using these special geometrical sections, to much research have been done from the mid-twentieth century. The Wake Equalizing Ducts (WEDs) in addition to conduct the more uniform fluid flow to the propeller disk (which causes to improve the propeller operation), affect on flow separation in ship stern zone and will decrease the separated flow zone.... 

Generally, Vessels at sea are exposed to water waves. Large displacement of the vessel affects its performance, passengers’ and crews’ activities or duties. Based on the type of the displacement (translational/rotational) and the orientation about the reference axes, floating vessels are collapse onto 6 distinct categories. One of the above-mentioned displacements about the reference axis is rolling motion. Rolling motion is the rotation of the vessel about its longitudinal axis. This displacement may lead the commuters or crews to seasickness. Furthermore, greatness of this displacement increases the probability of damage to the goods. Moreover, performance of the propulsion systems grows...