Based on the idea of adjoint method and the dynamic evolution method,a new optimum aerodynamic design technique is presented in this paper.It can be applied to the optimum problems with a large number of design variab...Based on the idea of adjoint method and the dynamic evolution method,a new optimum aerodynamic design technique is presented in this paper.It can be applied to the optimum problems with a large number of design variables and is time saving.The key of the new method lies in that the optimization process is regarded as an unsteady evolution,i.e.,the optimization is executed,simultaneously with solving the unsteady flow governing equations and adjoint equations.Numerical examples for both the inverse problem and drag minimization using Euler equations have been presented,and the results show that the method presented in this paper is more efficient than the optimum methods based on the steady flow solution and the steady solution of adjoint equations.展开更多
The ship hull is simplified as a free beam with varying sections. Based on hydroelasticity and explosion mechanics theory,mechanical model and kinetic equation for hull girder vibration under non-contact explosion are...The ship hull is simplified as a free beam with varying sections. Based on hydroelasticity and explosion mechanics theory,mechanical model and kinetic equation for hull girder vibration under non-contact explosion are established. The equation is solved by Wilson-θ algorithm. On the basis of the above principles,a structure kinetics analysis program is compiled. The dynamic response of supposed warship under air explosion is calculated conveniently and quickly. Under the explosion condition designed in the paper,the positive pressure period of non-contact explosion wave is much less than the natural periods of the first four modes of hull girder and the resonance of ship girder overall vibration can be avoided. The ratio of midship maximum moment to ultimate bearing strength under non-contact explosion accelerates with the increment of impact factor.展开更多
文摘Based on the idea of adjoint method and the dynamic evolution method,a new optimum aerodynamic design technique is presented in this paper.It can be applied to the optimum problems with a large number of design variables and is time saving.The key of the new method lies in that the optimization process is regarded as an unsteady evolution,i.e.,the optimization is executed,simultaneously with solving the unsteady flow governing equations and adjoint equations.Numerical examples for both the inverse problem and drag minimization using Euler equations have been presented,and the results show that the method presented in this paper is more efficient than the optimum methods based on the steady flow solution and the steady solution of adjoint equations.
文摘The ship hull is simplified as a free beam with varying sections. Based on hydroelasticity and explosion mechanics theory,mechanical model and kinetic equation for hull girder vibration under non-contact explosion are established. The equation is solved by Wilson-θ algorithm. On the basis of the above principles,a structure kinetics analysis program is compiled. The dynamic response of supposed warship under air explosion is calculated conveniently and quickly. Under the explosion condition designed in the paper,the positive pressure period of non-contact explosion wave is much less than the natural periods of the first four modes of hull girder and the resonance of ship girder overall vibration can be avoided. The ratio of midship maximum moment to ultimate bearing strength under non-contact explosion accelerates with the increment of impact factor.
