Abstract
The fuel saving device "Super Stream Duct" was developed in 1989 using Hitachi Zosen's original technological knowledge, and it's fuel saving effect has been confirmed through a large number of model tests and sea trials. Almost every large full body ships built by Hitacihi Zosen have been equipped with SSD. In this study, we try to simulate the flow field around the ship equipped with SSD, and investigate it's hydrodynamic effects on the propulsive performance by CFD applying the overlaid grid method to NICE-code. Firstly, in order to examine availability of the overlaid grid method, we estimate the rudder drag by this method and compare with that of the single grid method and model tests, We confirm that the accuracy of estimated thrust at the leading edge and the rudder drag by this method is remarkably improved. Next, we apply this overland grid method to SSD together with the rudder. The estimated effects of SSD on the wake distribution at propeller position, the viscous resistance (form factor K) and selfpropulsion coefficients (1-Wt, 1-t) show good agreements with results of model tests. Then we make some considerations on the mechanism of improved effects of SSD on the propulsive performance.
