The Study Of Resistance Prediction Method And Performance On Trimaran And Trimaran With Stern Flap

Due to the development of modern shipping industry and the needs of the military use,modern ships must have higher overall performance, including a high-resistance performance,seakeeping performance, maneuverability, etc. Due to the restrictions of the ship, forconventional displacement ship, all aspects of performance improvement had almost reacheda limit, compared with the conventional displacement monohulls with the same displacement,through the rational distribution, while reduced resistance in high-speed segment, it could alsoimproved stability, increased deck area, improved the seakeeping performance. It had verybroad application prospects in military vessels and civilian vessels.As it had get a prove that stern flap could improve the hydrodynamic performance and ithad been applied to a real ship, but the major commercial software is based on the theory ofviscous flow, it would take longer computation time and the accuracy needed to be improved.Based on the method of DAWSON, this paper developed trimaran wave resistance calculationprogram, and what was more, this paper considered the special treatment for the square sternof the ship as well as the installation of stern flap and do some research on the drag reductionperformance of the stern flap. Meanwhile, in order to contrast and verify the correctness of theresults, using ICEM software to Modeling and meshing the same model, and using thecommercial CFD software STAR-CCM+to calculate the same ship.This article selected mono-hull wigley ship and three-hulls wigley ship and utilitytrimaran, using the DAWSON method and STAR-CCM+calculated resistance value, andcompared with the experimental values, it could verify the correctness of the method. On thisbasis, choosing a trimaran with different stern flaps, and the length of the stern flaps are1%,1.5%,2%waterline length of the main hull, using the two methods to calculate resistancevalue, and compared the results. Finally, considered the lateral position of the side body forthe resistance performance of the trimaran. Using the two methods to calculate the resistanceof6kinds of ship (the two lateral positions and three lengths of the stern flap), analyzed andcompared the final results, did the research on the influence of the transverse side bodyposition of the trimaran to the drag reducing performance of the stern flap with differentlengths.The study shows that it’s feasible to forecast the resistance of the trimaran with the calculation procedure of DAWSON method. To the resistance of the trimaran, the stern flaphas a drag reducing speed area, different transverse position of the side body, will change thedrag reducing speed area. To the trimaran with the transverse spacing between10%and15%of the main hull waterline length, The best drag reduction region for the Froude number isgreater than0.35and less than0.45. And the transverse position of the side body has a biginfluence on the choose of the length of the stern flap. To the trimaran with the transversespacing between10%and15%the main hull waterline length, the best length of the stern flapis between1%and2%of the main hull waterline length. This illustrates that the choose of thestern flap is not only associated with the hull form and the main scale, but also with the sidebody transverse position.