Further Development and Optimization of the Ballast-Free Ship ...

Figure 3.5: Stern Pressure Coefficient of the Ballast-Free Bulk Carrier
(discharge Sta. 17 – 90 min)
Figure 3.6: Stern Pressure Coefficient of the Ballast-Free Bulk Carrier
(discharge Sta. 19 – 90 min)
Additional runs were performed to investigate the flow rate effect on the resistance.
Specifically, runs were made for an exchange time of 120 min, and thus, a slower water
discharge, and also an exchange time of 60 min leading to higher discharge velocities. The
first, slower case was investigated using the discharge location near Station 17 as this is a
relatively higher pressure region which is less likely to provide a high exchange rate. The
computed pressure drag coefficient has a value of 0.884e-3 and the friction drag coefficient
has a value of 3.375e-3. The computed pressure drag coefficient value corresponds to a
substantial reduction compared to the 90-min water exchange case with discharge from the
same location. The resulting form factor value is 0.299. The pressure coefficient contours at
the stern of the vessel in this case are shown in Fig. 3.7.
Figure 3.7: Stern Pressure Coefficient of the Ballast-Free Bulk Carrier
(discharge Sta. 17 – 120 min)
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