Experimental investigation of the effect of sail geometry on the flow around the SUBOFF submarine model inspired by the dolphin’s dorsal fin

The geometric shape of the submarine sail has a significant effect on the flow uniformity amount in the submarine impeller plane. In the present study, using a Hotwire and a five-hole probe, the downstream flow field for the three sail in the SUBOFF submarine model was investigated. Two of the sails have the same NACA0018 cross-section and height, one of which has a fillet on the leading-edge. The third sail has the NACA0018 cross-section which is shaped like a dolphin's dorsal fin. In this study, the rotational field of the vortex downstream of the sail has been studied. The presence of fillets at the leading-edge of the sail significantly reduces the amount and intensity of the vortex. The sail with a dolphin's dorsal fin geometry also has a significant effect on improving the flow quality. In addition, as the distance from the sail increases downstream, the wake becomes weaker.