Research On Environment Comparability Of Underwater Explosion

In this paper, numerical simulation method is used to solve some problems about the comparability research of underwater explosion.First the shortages of the traditional impulsive factor for describing the impulsive environment of underwater explosion are showed. Double cylinder shell structure is used to solve and simulate the underwater explosion effects. The results show that traditional impulsive factor can describe the extreme degree of the impulsive environment, but it has some limitations without considering the spherical characteristics of shock wave. So the traditional impulsive factor can not be used in describing the structure response near the detonator.According to the shortages of the traditional impulsive factor describing the near field explosion, the paper amends the traditional one so that a new kind of impulsive factor is defined which has more extensive scope of use and higher precision. For a certain model, the new impulsive factor can describe the impulsive environment exactly. With the same impulsive factor, the impulsive response of the structure is equivalent. The bigger the impulsive factor is, the greater the response and vice versa. The characteristics of the new impulsive factor help to the numerical analysis and experiment research of ship impact environment. For the numerical analysis, only a few working conditions are needed to know the shock response characteristics roundly so that large amount of time is saved. Through above analysis we can conclude that the new kind of impulsive factor has a great improvement and can be used in the real project easily. In this paper, dynamic numerical simulation method is used to probe into the similar responses of the prototype and scale structure when subjected to underwater explosion. The numerical experiment shows that the explosive energy, peak pressure, structural dynamic response and stress approximately tally with the elastic scaling laws. Using the elastic scaling laws, model experiment can effectively predict the shock vibration characteristics of prototype structure.Finaly the limitation of using the elastic scaling laws into the research on the anti-shock experiment of ship is put forward. If all the parts are scaled in the same proportion of geometry, the dimension of some parts (e.g. section bar, etc.) may be too small to construct the practical model. Hence, the similar model is considered as basic standard form, and then model is changed to some extent of variation corresponding to real condition. The variant model is also studied in the purpose of obtaining the useful information and experimental results close to practical situation. The material equivalence method and plate thickness sharing method are applied in this paper. Finally the formula is given for choosing the suitable scale parameter. The choosing range described in this paper is 1～λ_max.