The Research Of The Location Of Side Hulls Of Trimaran And Wave Making Interaction Based On The Method Of Mixed Optimization

As a new kind of high performance ship, trimaran is attracting more and more attentionand it has been already widely applied in civil transportation and military. The design andconstruction of trimaran is different from monohull because of its outrigger hulls. Theoutrigger hulls influence trimaran’s stability, seakeeping performance, speed and poweringperformance, maneuverability and etc. The influences of outrigger hulls are comprehensiveand even contradictory to each other. Hence it is necessary to find the right position of theoutrigger hulls by the method of optimization.There is much research about the optimization of the position of outrigger hulls. It isclear that different method has its respective advantages and disadvantages. But it is uncertainthat which method is appropriate for the optimization of trimaran or other multi hull ship. Theauthor made a deep research on the calculate method of wave resistance of trimaran based onthe Noblesse slender ship theory. In this paper simulated annealing, chaos algorithm andgenetic algorithm are analyzed. Two mixed optimization methods are created between them.Finally, a better method is chosen to optimize the position of the outrigger hulls.In order to calculate the wave resistance of a trimaran, a correction method of Noblesseslender ship theory is verified through a calculation of a trimaran. The comparison betweensimulated annealing genetic algorithm and genetic algorithm is made and so is the onebetween chaos genetic algorithm and genetic algorithm. It is proved that the mixedoptimization methods are better than the simple genetic algorithm. Some of the parameters areanalyzed of the mixed optimization methods. Several schemes are calculated and thecomparisons are made between them so that the parameters are determined. The optimizationresult between simulated annealing genetic algorithm and chaos genetic algorithm iscompared. It is found that the result of two methods is almost the same but the convergencerate of the simulated annealing genetic algorithm is a little higher than the chaos geneticalgorithm. Therefore simulated annealing genetic algorithm is chosen as the betteroptimization method of trimaran. Through analyzing it is found that the number of iteration,the population size and the initial temperature influence are associated with the optimizationresult. But the coefficient of temperature and the rate of mutate are associated with the convergence rate. The impact of the parameters on the wave resistance is not the same atdifferent Froude number. When the Froude number is between0.5and0.6wave resistance ischanging rapidly with the parameters.At last a wigley trimaran is optimized by the method of chaos genetic algorithm. Thebest position of the outrigger hulls and the corresponding coefficient of wave resistance aredetermined. And a refined researching is made so that the distribution of the position of theoutrigger hulls is calculated in detail. It can be found that the longitudinal position of theoutrigger hulls will influence the wave resistance much more than the horizontal position ofthe outrigger hulls. And the distribution of the longitudinal position of the outrigger hulls ismuch widely than the horizontal position of the outrigger hulls.