不同侧滑角下射弹高速入水流固耦合特性

Fluid-structure Interaction Characteristics of High-speed Projectiles at Different Sideslip Angles during Water Entry

摘要:

入水初始扰动对射弹高速入水稳定性与结构变形具有重要影响。初始扰动同时包含攻角和侧滑角，但当前的研究主要集中于攻角的变化。为获得侧滑角对射弹高速斜入水流固耦合特性的影响，基于计算流体力学与计算结构力学模型，建立双向流固耦合数值计算方法，研究了侧滑角 ? = 0^。_,1^。_,2^。_,3^。_,4^。_,5 下射弹在入水速度 v=700 m/s， 入水角?=3^。 时的入水空泡演化、动力学和结构响应特性规律。结果发现：1）射弹高速倾斜入水过程中，侧滑角会对射弹的入水弹道轨迹产生影响，当侧滑角小于临界值时，随着侧滑角的增加，弹道仍呈直线，空泡形态也较为规则，但射弹的偏航运动持续增强；当侧滑角大于临界值后，射弹的运动轨迹会因射弹弯曲变形产生弯曲，并出现抬头出水运动，空泡也会发生弯曲变形。2）射弹入水弹体变形主要以弯曲变形为主，造成的拉伸塑性应变数值略大于压缩变形。且塑性应变非持续增长，存在阶段增长特性，增长速率越大，稳定段维持时间越短。

Abstract:

The initial disturbance of water entry has an important influence on the stability and structural deformation of the high-speed projectile. The initial disturbance includes both the angle of attack and the sideslip angle，but the current research on the initial disturbance mainly focuses on the change of the angle of attack. In order to obtain the influence of the sideslip angle on the fluid-structure interaction characteristics during the oblique water entry of the projectile，a fluid-structure interaction numerical method based on the computational fluid dynamics and computational structural dynamics model is established. The supercavity evolution，dynamics and structural response characteristics of the projectile are studied when the water entry velocity v=700m/s. It is found that：1）During the high-speed oblique water entry process，the sideslip angle affects the trajectory of the projectile. When the sideslip angle is less than the critical value，with the increase of the sideslip angle，the trajectory is straight，and the shape of the supercavity is regular，but the yaw motion of the projectile is strengthened. When the sideslip angle is bigger than the critical value，the trajectory will be curved due to the bending deformation of the projectile，the projectile head will rise out of water，and the supercavity will also bend and deform. 2）The deformation of the projectile during water entry is mainly bending deformation，and the value of tensile plastic strain is slightly larger than that of compressive deformation. The plastic strain does not grow continuously，and there is a growth stage. The larger the growth rate，the shorter the maintenance stage.