Precision-guided projectiles (PGPs) experience severe shock loads during launch emanating from the propellant gases and the surrounding air. The complex flow environment that exists within the confined space of the barrel and at muzzle exit is significantly influenced by the speed of the projectile, the compressibility of the air, and the rapid state transition of the projectile from the confined volume of the barrel to the surrounding free space. In this effort, we extend our earlier vacuum work (Yin et al. in Int J Mech Mater Des 10:439–450. https://doi.org/10.1007/s10999-014-9255-0 , 2014) by performing comprehensive and a more realistic multiphysics simulations of the dynamics of the entire launch process of a projectile accounting for the intense combustion pressures of the propellant, the large accelerations experienced during the launch, and the induced shock waves. Our numerical model successfully captured the development and progression as well as the interaction of the projectile with the induced shock waves. Specifically, the model identifies the intense pressures generated by the propellant that result in supersonic flow conditions within the confined space of the barrel. This supersonic flow within the barrel leads to a wave front that travels ahead of the projectile creating a normal shock wave in the barrel. Once the normal shock crosses the muzzle exit, it diffracts into three types of shock waves: precursor, bow, and base. These shock loads pose a significant threat to the embedded electronic systems (EES) necessary for the operation, guidance and control of these PGPs. Our model further reveals that the projectile will experience a reduction in velocity as a result of induced frictional drag and interaction with the induced shock waves. This study will assist in the design and development of appropriate encapsulation techniques necessary for the protection of EES.

中文翻译：

---

精确制导弹丸发射动力学：流固耦合

精确制导射弹 (PGP) 在发射过程中会承受来自推进剂气体和周围空气的严重冲击载荷。枪管密闭空间内和枪口出口处存在的复杂流动环境受弹丸速度、空气压缩性、弹丸从枪管密闭空间快速状态转变的显着影响。周围的自由空间。在这项工作中，我们通过执行全面以及对弹丸整个发射过程的动力学进行更逼真的多物理场模拟，其中考虑了推进剂的强烈燃烧压力、发射过程中经历的大加速度，以及诱发的冲击波。我们的数值模型成功地捕捉了弹丸与诱发冲击波的发展和进展以及相互作用。具体而言，该模型识别了推进剂产生的强烈压力，这些压力会导致枪管有限空间内的超音速流动条件。枪管内的这种超音速流动导致波前在弹丸之前行进，在枪管中产生正常的冲击波。一旦正常激波穿过枪口出口，它就会衍射成三种类型的激波：前驱波、弓波和基波。这些冲击载荷对这些 PGP 的操作、引导和控制所必需的嵌入式电子系统 (EES) 构成了重大威胁。我们的模型进一步表明，由于诱导摩擦阻力和与诱导冲击波的相互作用，弹丸将经历速度降低。这项研究将有助于设计和开发保护 EES 所需的适当封装技术。