Research On The Resistance Calculation And Ship Optimization Method On The Inland Maritime Patrol Vessel

The maritime patrol vessel is the transportation facility for maritime affairs department to patrol and enforce laws daily.Their main responsibilities are to patrol maritime field,give publicity to maritime laws and regulations or knowledge and information about ship navigation safety,rush to deal with maritime emergency and rescue,and protect the transit of special and large ship or fleet.Due to the importance and urgency of the patrol vessel,the research on its speed has been paid more and more attention by many researchers.At present,the designers in Chongqing use the empirical formula to estimate the ship's resistance and the hull lines design process is usually based on parent ship when they are doing the ship's scheme design.The subjectivity of designers is very strong,which makes it difficult to get the best hull form with powering performance.In order to improve the design quality of inland ships,this paper takes the 33 m maritime patrol vessel as the research object,and studies the resistance calculation method and the hull lines' optimization method of the inland maritime patrol vessel.First of all,this paper uses the Auto CAD LISP language to numerate the atlas of the Ayre's method,establishes the corresponding data table,and corrects the coefficients of the research objects.The resistance calculation program based on Ayre's method is developed by MATLAB software,and the feasibility of the program is verified by comparison and analysis of the program calculation results,test results and Ayre's method calculation data.On this basis,the resistance of this maritime patrol vessel is calculated at five kind of ship speed by this program.This method can basically achieve the purpose of fast forecasting ship resistance in the scheme design stage.Secondly,the 3D ship model is drawn by the 3D modeling software CATIA based on the assured ship hull lines.This 3D ship model is introduced into ship hydrodynamic simulation software SHIPFLOW to simulate the resistance of the maritime patrol vessel.And the figures of waveforms and the longitudinal section wave at different speed are obtained.The resistance values calculated by empirical formula method and SHIPFLOW numerical calculation of resistance values are compared and analysed,the results show that the numerical simulation results are reliable.Finally,two methods of delta shift surface and delta shift in CAESES software are applied to modify the bow line of the maritime patrol vessel.The ship hull lines optimization is carried out with the objective of minimizing the wave-making resistance by using the Sobol variable design method and the NSGA-? global optimal algorithm successively,and the parameters of the shape line deformation are taken as the design variables and the drainage parameters are used as the constraint conditions for the objective function under the design speed.Then the total resistance of the pre-and post optimized vessel are computed severally by numerical simulation method.And the results are compared and analyzed to get better hull form with better resistance performance.The results show: the bow type line extending outward in a certain range can reduce the wave resistance in the limited displacement.At the same time,due to the small change of the wet surface area pre-and post optimization,the variation of viscous resistance is not obvious,and the total resistance is improved by the decrease of the wave making resistance.This paper's research achievements have applied value of the ship's resistance calculation and the hull lines' optimization for inland maritime patrol vessel.And it puts forward some solutions to the problems about the inland vessel's design such as arbitrariness of hull lines design,low computation efficiency and low accuracy of resistance calculation at the present stage.