Study On Ship-form And Hydrodynamics Of High Seakeeping Performance Hybrid Monohull

In high performance ship development process, improving seakeeping performancebecomes the consensus of the researchers. Harbin Engineering University developed a hybridmonohull. The hybrid monohull has a built-up appendage below the bow, which consists ofstreamlined semi-submerged body and a pair of fins. Compared with original ship, the hybridmonohull has almost the same resistance and much better seakeeping performance. The workin this paper is to design new hybrid monohull with better resistance performance andseakeeping performance by transforming the lines of main hull and adding new appendage,and do research on hydrodynamic performance of the new ship by theoretical calculation andmodel test.The configuration concept of new hybrid monohull is using deep-V main hull to improvethe seakeeping performance, adding stern flap to improve the resistance performance whichdegraded by deep-V hull, and finally developing the new hybrid monohull by integratingdeep-V main hull, built-up appendage and stern flap.Under the guidance of above concept, several deep-V hull programs are designed on thebasis of one round bilge ship by parent type transformation method. The program which hasthe best resistance performance is taken as the main hull of the hybrid monohull. Then, thedimensions and installation form of the built-up appendage and stern flap are designed, withthe target of improving seakeeping performance and resistance performance. The models ofdeep-V hull and new hybrid monohull sailing in still water are calculated by CFD softwareFluent. By comparing the resistance and flow field characteristics of two programs, theinfluence of built-up appendage and stern flap to resistance performance is analyzed.Then, the model test is carried out to analyze the resistance and seakeeping performanceof several programs, including original deep-V monohull (V0program), deep-V hybridmonohul (Va program), and deep-V hybrid monohull with stern flap (Vaf program). Bycomparing the test results, comprehensive performance of Vaf program is analyzed, and also,the effect on seakeeping performance and resistance performance of built-up appendage andstern flap are analyzed.Using traditional strip method to predict longitudinal motion of hybrid monohull, theresults can not reflect the effect of built-up appendage and stern flap. This paper calculates thecorrection hydrodynamic coefficients of the hybrid monohull with lateral flow theory methodand RANS equation method, then predicts the longitudinal motion by STF method. Bycomparing the predicted results with the model test results, it shows the calculation accuracy of two methods and which method is better for predicting the longitudinal motion of hybridmonohull.Finally, this paper optimizes the main dimensions and installation location of built-upappendage by using genetic algorithms, with the target of minimum bow acceleration. Theresult shows that it has good effect to optimize the configuration of hybrid monohull, theoptimization program is instructive to the design work.