弹体出水引起的非稳态流场数值计算方法

Numerical calculation method for the unsteady flow field induced by missiles flying out of the water surface

针对双渐近法不能用于分析有初始航速结构或大幅运动结构的流固耦合问题的局限性,在二阶双渐近法的基础上,将运动非线性引入双渐近法,采用改进的双渐近法研究弹体出水砰击引起的非稳态流场,给出了不同阶段的流场动态特性以及各个特征时间点流场动压力的空间分布情况.探讨了弹体出水时双峰值的产生机理、弹体局部结构可能会发生的拍振现象以及空泡区随弹体出水时的变化特征.研究表明弹体出水经历非稳态、稳态、非稳态、稳态4个阶段.

Because the doubly asymptotic approximation method cannot be used in the analysis of the fluid-solid coupling problem with initial velocity or large amplitudes structures, an improvement known as the nonlinear doubly asymptotic approximation was presented, which introduced motion nonlinearity to the DAA. The newly modified NDAA method was then applied to the computation of an unsteady flow field induced by the slamming of a missile body flying out from under the water. The research results show that the process of the missile body flying out of the water can be divided into four stages： unsteadiness, steadiness, unsteadiness, and steadiness. The dynamic pressure variation was then given along with the time of the four stages and the pressure distribution in space. Lastly, the mechanism of the double peak values and the local slapping phenomena in the process of the missile flying out of the water were discussed.