10CrMo9-10
2011年5月2日 by admin
【Abstract】 Ship oscillation motion is the major aspect in the research of ship seakeeping performance. Accurate evaluation of added mass, damping coefficients and wave forces is of great important to predict the motion and hydrodynamic performance of a moving ship in waves. Traditionally, obtaining the hydrodynamic coefficients mainly depends on potential flow theory method which has been widely used for predicting motions of ships in waves and physical experiments method. However, the linear potential flow theory neglects viscosity and nonlinear factors, and the ability would be limited for dealing with the strong nonlinear problems. Without correction, the results will be poor. In addition, model tests in physical tank are not only time-consuming but also strenuous. Its results are easily affected by testing instruments. Along with the development of the computer science and numerical technology, numerical simulation has become a critical technique in the research field of ship and ocean engineering. The numerical tank based on viscous flow theory will be a more direct and efficient way to solve hydrodynamic problems.On the basis of reviewing and summarizing the recent research progress on radiation and diffraction problems of ships, the work in the following aspects has been carried out:Firstly, a numerical wave tank is established based on CFD theories, which is modeled as a physical tank. Numerical simulations and analysis on radiation problems of moving ships with different forward speeds are then presented in the tank, which include simulations of forced heave10CrMo9-10
and forced pitch oscillations of moving Wigley-III. An approach to evaluate and analyze hydrodynamic coefficients is introduced to deal with the measured forces on the ship. The added mass and damping coefficients of various oscillating modes have been calculated and agree well with the experimental data from Delft University of Technology (DUT).Secondly, numerical simulation on diffraction problems of moving ships in waves are carried out in the numerical wave tank. Regular waves are successfully simulated and an artificial damping scheme is applied for the numerical wave absorption. Wave forces of the retrained ship model Wigley-III advancing in waves with the incident wave angle at 180o and 150o are computed respectively. The numerical results are compared with the corresponding ones of potential flow theory and the experimental data from DUT, and show good agreement with them.Results indicate that present method can not only give correct hydrodynamic coefficients and wave forces of moving ship but also detailed information of the flow. Undoubtedly, it has the potential to be applied in more wide research fields and provides broad prospects for the research on hydrodynamic performances of ocean and offshore structures.
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