| DDG1000 is a famous American Zumwalt destroyer with a length of 600 feet,a width of 80.7 feet,a design draught of 27.6 feet,and a speed of 30 knots.The bulbous bow is added,which has the effect of improving the speed and wave resistance of the ship.On this basis,parametric modeling of the hull of the improved DDG1000 according to the scale ratio of 1:70,optimization of the hull form and installation of combined appendages,further improve the speed and wave resistance of the ship.The specific work content is as follows:First,according to the influence of ship type characteristic parameters and characteristic parameter curves on hull resistance performance,a fully parametric hull model was established using CAESES software,and the hydrodynamic performance calculation was performed using FINE/Marine software,and compared with the test results to verify the numerical simulation results reliability.Secondly,in order to improve the accuracy and speed of the optimization search when the ship type is optimized,a combination optimization strategy is proposed,and the advantages and disadvantages of the two combination optimization algorithms are compared.The total drag at the design speed of 2.02 m /s is taken as the optimization goal,and the constraint condition is that the displacement of the hull remains unchanged.The two combined optimization algorithms are used to optimize the ship type.On the basis of the same number of hull models,the calculation time is similar.The resistance of the generated hull model is the first group,and the resistance value of the second group of optimization algorithms tends to be concentrated A certain value falls into the local optimal solution.The combination of the first set of Sobol algorithm and NSGA-II algorithm has a greater advantage than the combination of the second set of Sobol algorithm and Tangent Search Method algorithm.After optimization,the total resistance is reduced by 14.89%,the friction resistance is reduced by 0.43%,and the remaining resistance is reduced by 36.9%.Under the condition of regular waves,the optimized increase in wave resistance is reduced,and the heave and pitch of the hull are also improved.Within a certain wavelength range,the effect of improving the heave and pitch of the hull is obvious.Under the condition that the motion response is improved,there is no need to continue to optimize.After the optimization of the ship shape,the bulbous bow changed significantly,and the bulbous bow changed to a bowed bulbous bow.The length and width of the bulbous bow changed less than the impact of the bulbous bow height on the hull resistance.Then,on the basis of the optimized ship type,the bow-shaped bulbous bow was changed into a duck-shaped bulbous bow.The first group of Sobol algorithm and NSGA-II algorithm were combined to optimize the duck-shaped bulbous bow.When the tongue-shaped bulbous bow is optimized,the form of the tongue-shaped bulbous bow is quite different from that of the optimized bulbous bow,which cannot meet the same displacement as the optimized boat.Therefore,the duck-shaped bulbous bow is optimized.At the time,the unit displacement displacement at the designed speed of 2.02 m / s was taken as the optimization goal,and the hull resistance before and after optimization was converted into unit displacement resistance,which was compared with the duck tongue bulbous hull resistance.After adding duck tongue bulbous bow,the total resistance per unit displacement is 0.251 at a speed of 2.02m/s,whichis 5.5% higher than that before optimization and 24.3% higher than that after optimization;at a speed of1.77m/s At that time,the total resistance per unit of displacement was 0.183,which was 2.7% less than before optimization and 9.6% more than after optimization.After the optimization of the ship shape,the resistance of the duck tongue bulbous bow added increases,indicating that this ship type is not suitable for adding the duck tongue bulbous bow.Finally,on the basis of the optimized ship type,first add the tail pressure wave board,use the first group of Sobol algorithm and NSGA-II algorithm combination to optimize the tail pressure wave board,with the total drag at the design speed of 2.02m/s as the optimization goal,The length,thickness and installation angle of the tail pressure wave board are used as design variables to optimize the tail pressure wave board.When the length of the tail pressure wave board is 0.0354 m,the thickness is 0.006 m,and the total resistance is the smallest when the installation angle is-6.875 °.After installing the tail pressure wave board,the total resistance is reduced by 16.99% compared with that before optimization,2.5%compared with after optimization,the frictional resistance is reduced by 0.14%,and the remaining resistance is reduced by 8.1%.It shows that the tail pressure wave plate can improve the tail flow field,and reduce the residual resistance by reducing the viscous pressure resistance.The installation of the tail pressure wave plate has almost no effect on the friction resistance.On the basis of installing the tail pressure wave board on the hull,the hydrofoil is installed on the bow and the triangular side fin is installed on the bulbous bow.The same optimization algorithm is used for optimization.The results show that the installation of the hydrofoil and the triangular side fin causes the total hull Increased resistance does not improve hull resistance.Under regular wave conditions,after installing the tail pressure wave plate,fins and hydrofoil appendages,the wave resistance increase increases,when ?/L exceeds 0.9,the wave resistance increase is less than the optimized,the heave and longitudinal of the hull after installation Shaking has been improved,and within a certain wavelength range,the hydrodynamic performance of the ship's hull after the installation of wake pressure waves,fins,and hydrofoil appendages under regular wave conditions has been improved. |
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