Numerical Computation And Experimental Study Of The Effect Of The Knuckles On FRP Fishing Vessels’ Resistance

After the study of the world FRP fishing vessel status and FRP fishing vesseldesign and production technology, it is found that ship design which can meet not onlyrequirements of fiberglass material’s mechanical properties, but also the reduction ofhull resistance, is an important way for the development of fishing industry of China.This paper aims at further study of this problem. By stiffness comparison with the roundbilge steel hull, Taiwan FRP fishing vessel with large knuckles proves to be moreconducive to the stiffness. However, only few research of the impact of knuckle on FRPfishing vessels’resistance is conducted in China, and this problem becomes the coreissue for this paper to study.Firstly, the round bilge hull was selected as a parent ship with the methods ofparent ship streamline extraction, surface cutting and sewing, surface reconstruction. Bychanging the length of the knuckles, three specific FRP fishing vessels with differentsmall knuckles were designed, and along with one large knuckle FRP fishing vessel,these ships were all selected as the research objects.Secondly, FLOW-3D software was used to obtain the numerical computationresistance of three specific of FRP fishing vessels with different small knuckles and oneFRP fishing vessel with a large knuckle. It was concluded that different knuckles lengthhas no significant effect on the resistance of FRP fishing vessels; Different knuckletypes have great impacts on the resistance on FRP fishing vessels.Finally, ship models of small and large knuckle FRP fishing vessels were made andship model resistance tests were conducted. Compared with the round bilge (which hasno knuckle) hull among the entire speed range, the resistance of small knuckles hullhave decreased. Among the speed of11-13.5kn, the small knuckles hull has the mostobvious drag reduction effect. Resistance reduction of the small knuckles hull is20%ofthe resistance of the round bilge hull, and40-60%of the large knuckle hull. Numericalcalculation and experimental study results proved that small knuckle hulls meet rigidrequirements, and have remarkable drag reduction effects. In addition, with the help ofFLOW-3D numerical calculation, the result curves trend and the experimental results curve match well. The error between numerical results and the experimental results isless than5%near the design speed.After the study on the small knuckle design of how to obtain the drag reductionand the stiffness enhancement and the impact of the knuckles on the hull resistance, thispaper provided reference for further research and development work of FRP fishingvessels.