Line Optimization Design And Seakeeping Analysis On Planning Hull

This paper, rooted in the project of Intelligent High-speed Unmanned Surface Vehicle (USV), aims to design a platform for USV, which has good performance in both resistance and seakeeping. In order to cut technology risk of research as well as making full use of the advantage of relatively mature and wide knowledge and experience, planing hull may be a suitable selection for USV. At first, a high-quality coastguard cutter in resistance performance is selected as mother boat. Then it is altered at some main characteristic parameters in term of the design rule in planing hull, such as deadrise, longitudinal center of gravity (LCG), length of chine and so on. So two pierce of boat design are produced, and a series of model towing tank tests in different configurations are made. Referring to the research fruit of spray resistance in recent years, the SIT resistance prediction method is amended, which is validated by the model test data and proves that it enhances the precision. The corrected method could be used as math model for optimizing. A conversion method of resistance basing on navigation similarity is founded, and proved that it is a simple and useful by contrast Froude conversion method. Also it is argued that the minimum ratio of two power of boat in different speeds is equal to the minimum difference of two resistance of the model in corresponded speeds. This conclusion lays a foundation for line optimization of boat. Herein that the difference between the top speed (40 knots) and the cruise speed (25 knots) which are required by the project is quite big, the paper gives such a method of line optimization that under guarantee of access to the top speed, the machine of boat should be under the most suitable work state (70%-80% of rating power) at cruise speed as soon as possible, that is, the ratio of two power of the two speeds is least, which is equal to the minimum difference of two resistance of the model in corresponded speeds according to the conclusion of resistance conversion. The corresponded speeds of model are 10m/s and 6m/s. To reach this goal, penalty function method and BP neural network are used for line optimization, and the result is validated by the corresponded model towing tank test, which shows that it is successful in term of resistance coefficient. Finally, the data of the three models in seakeeping test is analyzed and disposed. Since the amplitude response of boat movement is no longer linear when Fv (the Cubic Froude Number) is larger than 3.0. So spectrum analyzing method is not suitable at high speed phase. The paper just only makes spectrum analysis for the relevant low speed 2.4m/s state. For the relevant high speed 6m/s state, time zone analyzing method introduces. Owing to lacking of test equipments, the phase spectrum between the boat movement and the regular wave could not be got, so as transient analysis technology. Time series analysis which just depends on history data is used for boat movement short-range forecast, which takes good effects.