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Modeling and numerical simulation of interior ballistic processes in a 120mm mortar system.

机译：120毫米迫击炮系统内部弹道过程的建模和数值模拟。

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摘要

Numerical Simulation of interior ballistic processes in gun and mortar systems is a very difficult and interesting problem. The mathematical model for the physical processes in the mortar systems consists of a system of non-linear coupled partial differential equations, which also contain non-homogeneity in form of the source terms. This work includes the development of a three-dimensional mortar interior ballistic (3D-MIB) code for a 120mm mortar system and its stage-wise validation with multiple sets of experimental data. The 120mm mortar system consists of a flash tube contained within an ignition cartridge, tail-boom, fin region, charge increments containing granular propellants, and a projectile payload. The ignition cartridge discharges hot gas-phase products and unburned granular propellants into the mortar tube through vent-holes on its surface. In view of the complexity of interior ballistic processes in the mortar propulsion system, the overall problem was solved in a modular fashion, i.e., simulating each physical component of the mortar propulsion system separately. These modules were coupled together with appropriate initial and boundary conditions.;The ignition cartridge and mortar tube contain nitrocellulose-based ball propellants. Therefore, the gas dynamical processes in the 120mm mortar system are two-phase, which were simulated by considering both phases as an interpenetrating continuum. Mass and energy fluxes from the flash tube into the granular bed of ignition cartridge were determined from a semi-empirical technique. For the tail-boom section, a transient one-dimensional two-phase compressible flow solver based on method of characteristics was developed. The mathematical model for the interior ballistic processes in the mortar tube posed an initial value problem with discontinuous initial conditions with the characteristics of the Riemann problem due to the discontinuity of the initial conditions. Therefore, the mortar tube model was solved by using a high-resolution Godunov-type shock-capturing approach was used where the discretization is done directly on the integral formulation of the conservation laws. A linearized approximate Riemann Solver was modified in this work for the two-phase flows to compute fully non-linear wave interactions and to directly provide upwinding properties in the scheme. An entropy fix based on Harten-Heyman method was used with van Leer flux limiter for total variation diminishing. The three dimensional effects were simulated by incorporating an unsplit multi-dimensional wave propagation method, which accounted for discontinuities traveling in both normal and oblique coordinate directions.;For each component, the predicted pressure-time traces showed significant pressure wave phenomena, which closely simulated the measured pressure-time traces obtained at PSU. The pressure-time traces at the breech-end of the mortar tube were obtained at Aberdeen Test Center with 0, 2, and 4 charge increments. The 3D-MIB code was also used to simulate the effect of flash tube vent-hole pattern on the pressure-wave phenomenon in the ignition cartridge. A comparison of the pressure difference between primer-end and projectile-end locations of the original and modified ignition cartridges with each other showed that the early-phase pressure-wave phenomenon can be significantly reduced with the modified pattern. The flow property distributions predicted by the 3D-MIB for 0, 2, and 4 charge increment cases as well the projectile dynamics predictions provided adequate validation of theory by experiments.
机译：炮弹系统内部弹道过程的数值模拟是一个非常困难和有趣的问题。砂浆系统中物理过程的数学模型由非线性耦合的偏微分方程组组成，该方程组还包含源项形式的非均匀性。这项工作包括为120毫米迫击炮系统开发三维迫击炮内部弹道（3D-MIB）代码，并使用多组实验数据对其进行阶段验证。 120毫米迫击炮系统包括一个装在点火药筒中的闪光管，后动臂，散热片区域，包含粒状推进剂的装料增量和弹丸有效载荷。点火盒通过其表面的排气孔将高温的气相产物和未燃烧的颗粒状推进剂排入砂浆管。考虑到迫击炮推进系统内部弹道过程的复杂性，以模块化的方式解决了整个问题，即，分别模拟了迫击炮推进系统的每个物理组成部分。这些模块在适当的初始条件和边界条件下耦合在一起。点火药筒和研钵管包含硝化纤维基球形推进剂。因此，在120mm砂浆系统中，气体动力学过程是两相的，这是通过将两相视为互穿连续体来模拟的。从闪蒸管进入点火药筒颗粒床的质量和能量通量是根据半经验技术确定的。对于尾臂截面，基于特征方法，开发了一种瞬态一维两相可压缩流动求解器。迫击炮管内部弹道过程的数学模型提出了具有不连续初始条件的初始值问题，由于初始条件的不连续性，其具有黎曼问题的特征。因此，砂浆管模型通过使用高分辨率Godunov型减震方法求解，其中离散化是在守恒定律的整体公式上直接完成的。在这项工作中，针对两相流修改了线性近似Riemann解算器，以计算完全非线性的波相互作用并直接提供方案中的迎风特性。基于Harten-Heyman方法的熵修正与van Leer通量限制器一起使用，以减小总变化。通过结合未分解的多维波传播方法来模拟三维效应，该方法解释了在法向和倾斜坐标方向上传播的不连续性。对于每个组件，预测的压力-时间迹线都显示出显着的压力波现象，并对其进行了紧密模拟。在PSU处获得的测得的压力时间曲线。在阿伯丁测试中心以0、2和4的装料增量获得灰浆管后膛端的压力-时间曲线。 3D-MIB代码还用于模拟闪光管通风孔样式对点火盒中压力波现象的影响。原始点火盒和改进的点火盒的引爆端和弹丸端位置之间的压力差相互比较表明，采用改进的模式可以显着降低早期压力波现象。由3D-MIB预测的0、2和4装药增量情况的流动特性分布以及弹丸动力学预测为实验提供了足够的理论验证。

著录项

  • 作者

    Acharya, Ragini.;

  • 作者单位

    The Pennsylvania State University.;

  • 授予单位 The Pennsylvania State University.;
  • 学科 Engineering Aerospace.;Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 263 p.
  • 总页数 263
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 航空、航天技术的研究与探索;机械、仪表工业;
  • 关键词

  • 入库时间 2022-08-17 11:38:26

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