A CombustionModel for Explosive Charge Affected by a Bottom Gap in the Launch Environment

Launch safety of explosive charges has become an urgent problem to be solved by all countries in the world aslaunch situation of ammunition becomes consistentlyworse.However, the existing numericalmodels have differentdefects. This paper formulates an efficient computational model of the combustion of an explosive charge affectedby a bottom gap in the launch environment in the context of the material point method. The current temperatureis computed accurately from the heat balance equation, and different physical states of the explosive charges areconsidered through various equations of state. Microcracks in the explosive charges are described with respectto the viscoelastic statistical crackmechanics (Visco–SCRAM) model. Themethod for calculating the temperatureat the bottomof the explosive charge with respect to the bottomgap is described. Based on this combustionmodel,the temperature history of a Composition B (COMB) explosive charge in the presence of a bottom gap is obtainedduring the launch process of a 155-mm artillery. The simulation results show that the bottom gap thickness shouldbe no greater than 0.039 cm to ensure the safety of the COM B explosive charge in the launch environment. Thisconclusion is consistent with previous results and verifies the correctness of the proposed model. Ultimately, thispaper derives amathematical expression for themaximumtemperature of the COMB explosive chargewith respectto the bottomgap thickness (over the range of 0.00–0.039 cm), and establishes a quantitative evaluationmethod forthe launch safety of explosive charges.The research results provide some guidance for the assessment and detectionof explosive charge safety in complex launch environments.

Application of Modelica Based Multi- Domain Modeling and Simulation for Gravity-1

In the R&D phase of Gravity-1(YL-1), a multi-domain modeling and simulation technology based on Modelica language was introduced, which was a recent attempt in the practice of modeling and simulation method for launch vehicles in China. It realizes a complex coupling model within a unified model for different domains, so that technologists can work on one model. It ensured the success of YL-1 first launch mission, supports rapid iteration, full validation, and tight design collaboration.

Multi-agent Based Hierarchy Simulation Models of Carrier-based Aircraft Catapult Launch

With the aid of multi-agent based modeling approach to complex systems, the hierarchy simulation models of carrier-based aircraft catapult launch are developed. Ocean, carrier, aircraft, and atmosphere are treated as aggregation agents, the detailed components like catapult, landing gears, and disturbances are considered as meta-agents, which belong to their aggregation agent. Thus, the model with two layers is formed i.e. the aggregation agent layer and the meta-agent layer. The information communication among all agents is described. The meta-agents within one aggregation agent communicate with each other directly by information sharing, but the meta-agents, which belong to different aggregation agents exchange their information through the aggregation layer first, and then perceive it from the sharing environment, that is the aggregation agent. Thus, not only the hierarchy model is built, but also the environment perceived by each agent is specified. Meanwhile, the problem of balancing the independency of agent and the resource consumption brought by real-time communication within multi-agent system （MAS） is resolved. Each agent involved in carrier-based aircraft catapult launch is depicted, with considering the interaction within disturbed atmospheric environment and multiple motion bodies including carrier, aircraft, and landing gears. The models of reactive agents among them are derived based on tensors, and the perceived messages and inner frameworks of each agent are characterized. Finally, some results of a simulation instance are given. The simulation and modeling of dynamic system based on multi-agent system is of benefit to express physical concepts and logical hierarchy clearly and precisely. The system model can easily draw in kinds of other agents to achieve a precise simulation of more complex system. This modeling technique makes the complex integral dynamic equations of multibodies decompose into parallel operations of single agent, and it is convenient to expand, maintain, and reuse the program codes.

Simulation of two-dimensional interior ballistics model of solid propellant electrothermal-chem ical launch with discharge rod plasma generator

Instead of the capillary plasma generator(CPG),a discharge rod plasma generator(DRPG)is used in the30 mm electrothermal-chemical(ETC)gun to improve the ignition uniformity of the solid propellant.An axisymmetric two-dimensional interior ballistics model of the solid propellant ETC gun(2D-IB-SPETCG)is presented to describe the process of the ETC launch.Both calculated pressure and projectile muzzle velocity accord well with the experimental results.The feasibility of the 2D-IB-SPETCG model is proved.Depending on the experimental data and initial parameters,detailed distribution of the ballistics parameters can be simulated.With the distribution of pressure and temperature of the gas phase and the propellant,the influence of plasma during the ignition process can be analyzed.Because of the radial flowing plasma,the propellant in the area of the DRPG is ignited within 0.01 ms,while all propellant in the chamber is ignited within 0.09 ms.The radial ignition delay time is much less than the axial delay time.During the ignition process,the radial pressure difference is less than 5 MPa at the place 0.025 m away from the breech.The radial ignition uniformity is proved.The temperature of the gas increases from several thousand K(conventional ignition)to several ten thousand K(plasma ignition).Compare the distribution of the density and temperature of the gas,we know that low density and high temperature gas appears near the exits of the DRPG,while high density and low temperature gas appears at the wall near the breech.The simulation of the 2D-IB-SPETCG model is an effective way to investigate the interior ballistics process of the ETC launch.The 2D-IB-SPETC model can be used for prediction and improvement of experiments.

A capture probability analytic model for the electromagnetic launched anti-torpedo torpedo

With the unique characteristics,electromagnetic launch technology is applicable to launch shipborne anti-torpedo torpedo(ATT).This paper aims to establish an analytic model to pre-evaluate the capture probability of the electromagnetic launched ATT.The mathematics model of the multi-stage coilgun and the trajectory of the ATT is established for analysis.The influence factors of the capture probability are analyzed respectively,including the entry point dispersion of the ATT and the position dispersion of the incoming torpedo.Adopting the advanced angle interception mode,the ATT search model is obtained according to the positional relationship,and the course error is synthetically calculated according to the differentiation of implicit function.A geometric method to calculate the integral boundaries of the probability density function is proposed,based on the relative motion of the ATT and the incoming target.To verify the proposed integral model,the digital simulation and comparison is conducted.The results reveal that the variation trends and the calculation value of the proposed analytic model are coincident with the statistic results from Monte Carlo method.And implications of the results regarding the analytic model are discussed.

Application of transient burning rate model of solid propellant in electrothermal-chemical launch simulation

A 30 mm electrothermal-chemical(ETC) gun experimental system is employed to research the burning rate characteristics of 4/7 high-nitrogen solid propellant. Enhanced gas generation rates(EGGR) of propellants during and after electrical discharges are verified in the experiments. A modified 0D internal ballistic model is established to simulate the ETC launch. According to the measured pressure and electrical parameters, a transient burning rate law including the influence of EGGR coefficient by electric power and pressure gradient(dp/dt) is added into the model. The EGGR coefficient of 4/7 high-nitrogen solid propellant is equal to 0.005 MW-1. Both simulated breech pressure and projectile muzzle velocity accord with the experimental results well. Compared with Woodley's modified burning rate law, the breech pressure curves acquired by the transient burning rate law are more consistent with test results. Based on the parameters calculated in the model, the relationship among propellant burning rate, pressure gradient(dp/dt) and electric power is analyzed. Depending on the transient burning rate law and experimental data, the burning of solid propellant under the condition of plasma is described more accurately.

New Model Charade Sedan Cars launched

The Tianjin Mini-Automobile Factory is a main engine factory of the Tianjin Aotomoibile Industry (Group) Co. Ltd., and also a manufacturer of the Charade sedan cars of economy model. It is one of China’s four major sedan car production bases. In 1995, it formed a production capacity of 150 thousand sedan cars. The Charade sedan cars still occupy 60 percent market share of the national taxi market. The Tianjin Mini-Automobile Factory now has a total staff of 3,914. It covers an ama of 429,000 square metres,

过失速重新定向机动过程气动特性建模

以过失速重新定向技术为基础的自翻转越肩飞行器与传统越肩发射飞行器相比,具有响应时间短、机动性能高、射程远等优势。本文针对飞行器过失速重新定向机动过程,基于CFD动态计算数据分析了该过程中的飞行器气动特性,通过改进微分方程模型成功描述了机动过程中的迟滞环效应,同时验证了最小二乘支持向量机方法在此建模问题中的适用性。本文的建模方法可以准确捕捉飞行器过失速重新定向机动过程中的非线性非定常气动特性,为飞行器过失速重新定向机动控制律设计提供模型基础。

水压驱动两级提拉式水下发射装置内弹道建模

针对大深度环境水下发射技术需求,提出一种利用水压驱动两级提拉式水下新型发射方案。利用大深度环境高压水驱动两级活塞实现武器快速发射。建立武器出管过程动力学模型,开展高压水驱动方案原理验证试验,并与高压气体驱动方案进行了对比分析。研究结果表明:水压驱动与气体驱动方案的内弹道结果基本一致,高压水发射方案在大深度环境具有显著优势;加速度峰值出现在发射瞬时和级间转换过程,级间转换过程武器加速度存在显著的陡变现象;水下发射武器出管过程弹道预报结果得出,在发射水深100~500 m条件下,武器出管过程最大速度范围为7.4~15.3 m/s,最大加速度小于100 m/s 2;研究结果验证了水压驱动两级活塞式发射方案的可行性,为装置的进一步研制开发提供了设计依据。

弹丸定心部-身管接触模型及其应用

研究弹丸定心部与炮膛的接触现象对于理解弹丸膛内运动规律具有重要的意义,为此提出一个弹丸定心部-身管接触模型。假设定心部与阳线间的接触应力只沿阳线长度方向变化,将阳线表面简化成空间曲线;用阳线围成的笼形结构描述内膛的几何,提出了定心部与阳线的接触检测算法。将弹丸和身管沿着圆周方向展开,使用一个二维接触问题的解析解计算接触应力。针对接触应力的方根奇异性,采用Chebyshev-Gauss积分公式计算定心部与阳线的接触载荷。给出了确定模型参数的拟合方法和参数辨识方法。理论分析表明定心部与炮膛的接触刚度随着弹丸膛内行程变化。根据数值算例分析了弹丸质心偏移量对定心部与炮膛接触方式及前定心部磨损刻痕形成的影响。计算结果表明定心部受力的等效接触点并不位于定心部中心或棱线上。

水下运载器动力学仿真以及串级控制器参数优化

为了让水下运载器能够更好完成潜射无人机的跨介质机动,基于回转体结构以及ROV(Remote Operated Vehicle)驱动模式设计一种具有动力的潜射无人机水下运载器。根据该运载器的外形结构和驱动模式特点,对其进行动力学建模并设计一种串级控制器控制该运载器的六自由度运动参数,利用Matlab/Simulink进行仿真验证,最后利用Isight优化软件对该运载器的串级控制器参数进行优化,分别利用自适应DOE优化算法和Evol优化算法进行优化计算,经过优化后的串级控制器在六自由度上的轨迹跟踪效果均有提升,其中Evol优化算法优化效果更好,计算成本更小。

受空间约束时曲线钢箱梁步履式多点顶推策略

针对曲线钢箱梁多点步履式顶推同步控制难度高、往往受到各类空间约束限制的难题,为提高顶推施工的精确性与可靠性,应充分降低曲线顶推施工过程中的多点异向和异速顶推工况次数,根据尽量使得顶推过程中曲线箱梁各点顶推方向与速度相同这一基本原则,提出了受空间约束时曲线钢箱梁以平移和纠偏为主,旋转与调整为辅的顶推策略和方法,建立了各基本工法对应的顶推数学模型,并将其成功应用于兰州市某非对称曲线斜拉桥的钢箱梁顶推施工。研究结果表明:随曲线钢箱梁顶推行进,理论计算出的梁体尾部偏差值逐渐变大、梁体所需旋转角度逐渐变小,故曲线钢箱梁顶推初期宜多次采用旋转工法减小曲线夹角,后期宜多次采用纠偏工法减小轴线偏差;调整工法可有效减少其余工法的实施次数,其计算流程独立于其他工法,只与当前曲线钢箱梁到达的临时墩所在平面位置有关;曲线钢箱梁即将穿越桥塔等空间障碍物时,梁体与障碍物碰撞风险最大,而随顶推进程的继续,梁体与障碍物碰撞风险会逐步降低;该曲线钢箱梁顶推策略与方法思路明确、可操作性高,可大幅降低对多点步履式顶推系统的要求,提高顶推施工可靠性,适用于市政桥梁的曲线钢箱梁步履式顶推施工。

炮口振动特性对自动炮射击精度的影响研究

为研究炮口振动特性对射击精度的影响,以某型自动炮为研究对象,对模型做出合理假设,分析自动炮系统各部件之间的约束关系,基于火炮发射多体动力学理论,考虑身管柔性、机构间隙等因素,建立了自动炮动力学仿真模型;通过火炮水平射击时后坐和复进的后坐力及后坐位移曲线,验证了仿真模型的准确性。对单发和连发射击时的自动炮动力学特性仿真模型进行仿真计算,得到了该自动炮单发及连发射击时的炮口动态特性。根据各发弹丸出炮口瞬间炮口振动特性,初步计算了千米立靶密集度。仿真结果及立靶密集度计算结果对火炮射击精度的提高和结构优化具有一定的参考价值。

基于非平稳高斯过程的高空风场偏差建模方法

高空风场偏差建模方法对运载火箭气动载荷计算和总体性能优化具有显著影响。目前工程常用方法未考虑不同高度层风速相关性,所得样本与实际风场特征存在差异,难以精确预示火箭气动载荷。提出将U/V风速分量建模为关于高度的非平稳高斯过程,基于大量历史风场样本统计分析实际风场在不同高度层的特征参数,利用扩展最优线性估计方法生成与实际风场具有相同分布的子样。结果表明提出的方法相比传统手段能够从形态上更加准确表征真实风场剖面。基于真实飞行器仿真程序对风致载荷进行计算,结果显示该方法对气动载荷裕度的预示误差远小于目前工程方法,对提升火箭运载效率和放行概率具有重要意义。

大气空间和季节性气候特征对RLV升力式再入飞行的影响

为提升重复使用运载器(RLV)竞争力精细化设计边界,在融合3颗卫星载荷采集的大气数据基础上,采用大/小尺度扰动分别建模的方法,建立了沿RLV再入飞行轨道的全域参考大气模型,开展了大气密度空间性和季节性(1月、4月、7月和10月)气候变化对跟踪RLV高纬度升力式再入标准轨道的影响分析。结果显示季节性和轨道空间性变化带来的大气密度偏差特性和散布特性,会强烈影响跟踪标准轨道的终端分布特征。这表明引入大气参考模型可以提升RLV性能,降低运行成本。

液体运载火箭贮箱箱底厚度设计准则及轻量化

为进一步实现液体运载火箭贮箱箱底结构轻量化,在实际工况的约束下,综合现役箱底的载荷特点(贮箱箱底厚度参数和火箭运行内压值的理论关系),对贮箱箱底的结构进行参数化。提出剩余强度系数作为贮箱箱底的设计载荷指标,结合工况建立了箱底厚度设计准则,剩余强度系数不小于1时满足工程需要,并以此对箱底厚度进行优化。根据设计准则可以建立开口与箱底厚度的关系,更精确的给定设计箱底临界厚度值。建立的箱底厚度设计准则可以对已设计完成的贮箱箱底进行内压承载能力进行验算。运用实际工况数据验证了设计准则的可用性,并提出了旋压型箱底的厚度分区轻量化方法。此外,根据贮箱箱底管路接口、传感器接口各方面输入输出的交互影响,建立了贮箱箱底开口多约束评估模型。通过参数化平台实现方法的具体实用性及自动化建模。结果表明,旋压型箱底的厚度分区轻量化方法可以实现箱底平均减重约30%。参数化平台和自动化建模为提高贮箱箱底设计效率提供了一种新的方法。

发射载荷作用下特种车辆动态响应仿真分析与优化

基于HyperMesh-LS-DYNA有限元建模与仿真方法,探究了特种车辆在发射载荷作用下车体的稳定性问题。以某型特种车辆为研究对象,在车辆数值仿真模型中构建了悬架等相关柔性化组件,对车体在发射载荷作用下的稳定性进行分析,发现发射载荷未能均匀分散到各支撑结构,且在发射底座、 g-h轴对应轮胎与地面的接触压力较大,发射筒摆动幅度较大。基于上述结果,提出调整支腿结构的刚度阻尼系数和增加附加支撑结构两种优化方案,以达到减小车辆与地面的接触压力以及车体纵向摆动幅度的目的,并进行了仿真验证。结果表明,辅助支撑的数量与位置对车体稳定性的影响较大,靠近底座以及数量越多,对车体稳定的保持效果较好,其中在g-h轴之间增加一对附加支腿,底座接触力减少16%;在b-c、 g-h轴之间同时各增加一对附加支腿,底座接触压力减少20%,发射筒摆动幅度范围缩减12.1%。

中大口径加榴炮发射环境极限边界工况炮-弹-引耦合响应特性

针对中大口径加榴炮机械触发引信早炸时有发生,引信及其典型结构在内弹道高动态复杂力学环境下的响应特性不清晰、失效机理不明确等问题,建立了考虑身管中后期磨损、底排弹0号装药、弹丸最大装填角、弹丸与引信极限偏差等极限边界工况的内弹道环境炮弹引耦合动力学仿真模型。采用融合SPH和Lagrange的有限元计算方法,分析弹引典型机构响应特性,并通过底凹弹和底排弹典型工况测试数据对仿真模型的预测误差进行验证。结果表明,极限边界工况会对弹丸挤进阻力、前定心部与身管撞击力的时域分布特征以及运动姿态等造成显著影响,会对引信及其典型机构过载响应造成较大影响。相比底凹弹和底排弹常规工况,膛内弹丸与身管撞击力分别增大63.75倍和29.82倍,出炮口瞬间弹丸俯仰角分别增大8.69倍和6.71倍,偏航角分别增大3.89倍和1.75倍,膛内引信回转体轴轴向峰值过载分别增大19.49%和5.44%,径向峰值过载分别增大78.7%和1.44倍。极限边界工况下,膛内阶段引信发生强度失效的风险明显增大,出炮口后弹引初始章动角量值明显增加,飞行阶段异常作用的风险也会增大。相关研究对于探寻复杂动态力学环境中大口径机械触发引信失效机理,指导引信加固优化设计具有重要意义。

发射系统指向角度标校方法

针对传统瞄星方法存在的效率低和“受制于天”的问题,提出了一种基于模型的标校方法。该方法把安装平台抽象为分段线性的平板模型,其误差用俯仰、偏航、滚转3个参数表示,得到包含模型误差的指向角度。同时,采用高精度卫星导航设备建立虚拟空间基准,利用二者的等价关系,通过牛顿迭代法求解出误差参数,并进行修正。理论和仿真分析表明:只需要2个测量点就可以解算整个模型,提高了标校效率;只要基准点距离身管1 km以上,基准点的测量精度对标校精度的影响就可忽略;通过合理选择基准点,可以将指向角度标校残差控制在0.001 rad。

基于遗传算法的航天发射人员编组分配

针对航天发射人员编组分配主要依赖于任务经验、缺少理论支撑的问题,首先基于航天发射人员编组原则简要设计了人员编组构成,包括技术保障班组、发射班组和测试班组,其次以航天发射人员在三个班组内的工作效益值为基础,引入最大工作效益为优化目标,基于传统的指派模型构建了人员分配模型,最后基于遗传算法,通过十进制编码规则给出了人员分配模型的求解方法。针对具体算例,给出了人员编组分配结果,证明了相关方法的可行性和有效性。