The Simulation Of Wave And Its Effects On The Exceeding Water Process Of An Underwater Vehicle

When the missile approaches water surface in the process of underwater launching, it will be affected by wave inevitably, thus the parameter of the ballistic trajectory will be changed. Moreover the water-exit course also involves a severe gas-liquid mixing, so the fluid force on the missile surface is complex. Wave makes the asymmetrical force more complex, changes the missile attitude, even leads to a structural failure. So the study about the wave effect on the mechanical parameters and kinematic parameters of missile is significant.Experiment is the most time-consuming, money-consuming way to research the wave effect, so the numerical simulation is necessary. The numerical wave is the base of the numerical study. The quality of numerical wave decides whether the wave effect can be analysed accurately, and then the force on the missile body and other kinematic parameters can be obtained. In the present paper, the waves with different levels and different models were first simulated according to the velocity inlet boundary condition method by Fluent software. Then the wave quality was compared. The best wave model was at last chosen for the following research.On the base of the optimum numerical wave, the three-dimensional simulation model involving the missile moving was built, and then the wave effect on water-exit course of missile was investigated. Under the fifth wave level, the effects of wave force on the flow field and dynamic characteristics of the submarine-based missile were studied by simulating the wave impacting the static missile and the launching vertically in one-degree of freedom, as well as six-degrees of freedom. The simulation of the wave impacting the static missile demonstrates the variation and the magnitude of the fluid force on the missile in an entire wave cycle, which provides a foundation for the succeeding research. The fluid force when the missile exits water in different wave phase positions was analysed. The result shows that the forces are opposite when the missile exits water between the wave crest and the wave trough, and the force magnitude is larger in the case of wave crest.The wave effect on the missile attitude was studied in the models of six-degrees of freedom. Under the impact of wave, the missile attitude and position changes. Moreover the wave has an amplification effect on the missile attitude and fluid force.