The Research On Optimization Of Resistance Performance Of Partial Air Cushion Supported CATamaran

Partial Air Cushion Supported CATamaran (PACSCAT), featuring low draft, high speed and large carrying capacity, is an incorporation of ship-form characteristics of conventional high-speed catamaran, surface-effect ship and high-speed planing boat. This ship form is made easier to develop towards size maximization by its extraordinary stability and broad deck and demihull. However, as the hull size grows, the sharp increase of resistance restricts space of design, which makes it necessary to conduct research on resistance-optimization for PACSCAT. At present, research on hydrodynamic performance of this ship form relies mainly on model test. However, model tests may not be the best choice for rapidity design and performance optimization due to high costs and long cycles. In this paper,CFD( Computational Fluid Dynamics)methods are used to simulate towing-tank model tests of an upsized PACSCAT, and its resistance performance is researched and optimized based on the simulations.CFD numerical simulation methods are used in this paper to calculate resistance performance of PACSCAT. The validity of calculation results are verified through simulation of air cushion by building a model of plenum chamber that is consistent with that used in model test, and comparison of calculation results with that of model test. Then, incremental researches on several air cushion relevant parameters, aiming at resistance performance,where the influence of inflation flux of air cushion, width of air cushion, height of air seal and height of air cushion changing in a certain range on resistance,performance are studied respectively, and the influence mechanism is analyzed and discussed.With the help of modelFRONTER optimization platform, integrating effectively technologies such as optimization theoretical methods, CAD parameterized modeling and CFD numerical simulations, the optimization design framework of resistance performance of PACSCAT is established based on SBD (Simulation Based Design). Setting width and height of air cushion, height of air seal as variables, single-object optimization of overall resistance when Fr=0.36 is conducted for PACSCAT, through which single-point optimized ship form is obtained, with obvious resistance-reduction effect. Finally, considering the close association between resistance performance and speed, double-object optimization of overall resistance is conducted for PACSCAT when Fr=0.36 and Fr=0.66, response surface models are established for approximation of relationship between designed variables and target function, which is calculated using multi-object genetic algorithm, and resistance-optimized ship form is obtained in certain speed range.