Hull Form And Configuration Optimization Of High-speed Trimaran Based On Hydrodynamics

The acceleration of globalization leads to the quick development of high-speed marine transportation. Trimaran is an important high-performance ship type for high-speed marine transportation. Due to the fact that a trimaran has one center hull and two outriggers, enormous design parameters and the intricate effects on the trimaran’s behavior should be taken into account via the multidisciplinary optimization design method in order to balance the overall performances of the vessel and get the optimal solution. In this paper, a hull form and configuration optimization system based on the resistance and seakeeping of trimaran is established on which the hydrodynamic performances of a trimaran are investigated and a series of ship hull hydrodynamic optimization cases are performed and analyzed.In the investigation of trimaran’s resistance behavior, the comparison between numerical calculation and experiment result of the wave resistance and a relatively stable mesh method by means of commercial code is given. The clearance and stagger influences on the trimaran’s wave drag in various speeds are investigated. Based on the trimaran hydrodynamic optimization system, three measures including varying hull configuration exclusively, varying center hull form exclusively and varying both of these two factors are taken to optimize the wave resistance. It is discovered that when fast travelling, the outriggers locating aft the center hull is good for the wave resistance performance. The larger angle of risen bottom and deeper draft of center hull could make the hull form more sharp vertically and improve wave resistance performance. It is shown that varying hull configuration and center hull form simultaneously may contribute to better effects on wave drag performance.As for the investigation of sea keeping of trimaran, a database is established with various trimaran vessels in which the motion information of each vessel in head sea is calculated. With the meta-model technology, an approximate model is built to estimate the short term response of trimaran in head sea. Combined with reasonable seakeeping indexes, the impact of outriggers on seakeeping performance is analyzed and an optimization case of best outrigger location is performed. It is also introduced in this paper that an optimization of principal dimensions taken ship motion in waves into consideration is complemented in the preliminary design stage. The influences of the principal dimensions and parameters of trimaran on seakeeping indexes are discussed according to the optimization results. This also provides some reference on trimaran design.At the last part of this paper, a comprehensive optimization based on seakeeping and resistance is approached with multidisciplinary optimization method. The optimal hull form of minimum total resistance per unit displacement and maximum long term work index is reached. Meanwhile, the influence of seakeeping criterion is also investigated.