Design and Optimization of 3D Wagon Wheel Grain for Dual Thrust Solid Rocket Motors

The combination of various design and performance parameters in dual thrust solid rocket motors coupled with constraints may lead to a multitude of configurations. It is difficult to initially determine a suitable design without optimization. In this article, a methodology for the design of a 3D wagon wheel that provides two levels of thrust, namely boost phase thrust and sustain phase thrust, is investigated. The proposed framework consists of an integrated approach of grain design, computer aided design and hybrid optimization. A hybrid genetic algorithm and simulated annealing are used for optimization due to their robustness and capability to find global optimal solution. Several benchmark test functions are used to validate the performance of the optimization algorithm and solution. Maximization of the average thrust ratio and the total impulse are the objective functions under the given constraints.     

加速度对丁羟推进剂燃速影响的研究

通过试验研究了加速度场中丁羟推进剂的燃速的加速度敏感性。另外从加速度力作用下燃烧区压缩导致热反馈增大角度出发,建立了加速度条件下推进剂稳态燃烧模型,并编程计算、分析了影响推进剂燃速敏感性的因素,可为发动机内弹道设计提供参考。     

Solid Propellant Burning Rate From Strand Burner Pressure Measurement

Strand burner pressure–time data are analyzed to determine if the propellant burning rate can be extracted. This approach is based on strand burner pressure–time history that is related to the temperature change due to exothermic reaction heating of chamber gases and gas addition to the chamber by propellant combustion products. In support of this method, chemical equilibrium calculations were made to project product composition, internal energy, and other needed properties. A mathematical model was formulated and solved numerically and the calculated burning rates were compared with the experimental wire‐break time results provided simultaneously and with the propellant manufacturer's results, when available. The comparisons reveal that the approach has merit and that more accurate pressure determination coupled with additional thermochemical information and strand burner gas temperature measurements has the potential to make this approach a viable technique and one that can be applied in conjunction with other burning rate measurements. The proposed method is similar to a well‐developed technique which is commonly applied to ballistic powders but with adjustments for the differences in geometry, pressure, and time of event.     

固体火箭发动机装药端面燃烧燃速畸变现象分析

分析比较了引发固体火箭发动机装药燃速畸变的因素,如壁面附近的增塑剂、固化剂的迁移以及细氧化剂聚集等。认为固体装药燃速畸变现象产生的根本原因是壁面附近的氧化剂颗粒质量分数高于中心区域,氧化剂平均粒度低于中心区域。为验证这一理论分析,用基于粒状扩散火焰（GDF）模型得到的推进剂燃速计算公式,以氧化剂的含量和粒度为变量,计算了AP推进剂的燃速。结果表明,燃速计算值的变化趋势与理论分析结果相一致。     

Pressure Profile Prediction of Dual‐Thrust Rocket Motors under Uncertainties

Mathematical models that simulate the internal ballistics of solid propellant rocket motors are widely used in lieu of the expensive, hazardous, time‐consuming static firing experiments. Since they rely on the input of various measured data, these models are vulnerable to uncertainties that may deteriorate their prediction accuracy. Improving the accuracy of internal ballistics prediction can be achieved by coupling the mathematical models with optimization algorithm. This paper discusses the issues of uncertainties and their impact on prediction accuracy of developed mathematical models. The model handles two types of dual thrust rocket motors, where the impact of uncertainties is more pronounced since they include more geometric and ballistic parameters. The model is developed based on the fundamental principles of internal ballistics and is coupled with a commercial genetic algorithm optimization tool. Two static firing tests are conducted to assess the proposed optimized prediction model. It is found that prediction optimization via tuning the uncertain parameters has led to significantly improving the prediction accuracy. More importantly, the tuned uncertain parameters give better understanding and clearer insight of the phenomena taking place inside dual thrust solid propellant rocket motors.     

Correlations of Uncertainties of Composite Propellant Strand Burner Burning Rate Measurement for Quality Control

This study acquired, classified, and analyzed more than 3500 repeated‐measured steady state strand burner burning rate data from our quality control data bank as well as from open literature. The large size of consistent data from our resource were employed for the construction of a model that correlates burning rate standard deviations with average burning rates for both within‐batch lots and among‐batch lots. An increase in standard deviations with burning rates was observed for both correlations. Both correlations exhibit an R²‐statistic larger than 0.82 within burning rate range of 3.4–38.6 mm s⁻¹, and both correlations provide predictions in good agreements with some good quality published data. These two correlations may serve as feasible burning rate standard deviation tolerance reference when conducting composite propellants production quality control or burning rate data reproducibility checkup. Moreover, the confidence limits of parameters from the derived within‐batch correlation equation allow assessing the maximum pressure‐exponent uncertainties within selected burning rate range, thus provide insightful considerations to pressure‐exponent tolerance assignment for propellants under development or production.     

基于动力学过程的固体推进剂降速机理

根据朗缪尔单分子吸附原理和AP分解的质子转移机理,分别在AP晶体界面和气相混合区中确立物质守恒关系,分析了AP在不同分解速率下气相混合区中NH_3和HClO_4的气相分子浓度关系;将其与AP晶体气固交界面的反应强度进行关联,建立了一种能够分析压强变化状态对推进剂燃速影响的动力学机理,并推导了相应的物理过程,通过实验将AP/降速剂(CaCO_3或NH_4C_2O_4)的TG-DSC分析结果与药条燃速结果进行了对比。结果表明,该降速机理能够解释降速剂对推进剂燃速和压强指数的多种作用,CaCO_3能够使AP的热失重分解温度出现一定程度的前移,因此对控制推进剂的高压压强指数有利,而NH_4C_2O_4不具备这种效果。     

固体推进剂配方优化设计方法及其软件系统

概述了固体推进剂配方优化设计的进展及常用的优化方法,重点介绍了模式搜索法和遗传算法优化原理,通过一些典型实例介绍了具体优化计算方法。该优化方法和优化设计软件包(SPOD)可用于火炸药、化学及高分子材料配方优化设计中。附参考文献41篇。     

超声波燃速测试技术在固体推进剂研制中的应用

介绍了通过连续测量超声脉冲在推进剂中的反射时间,确定推进剂燃烧端面的位移,从而得到推进剂燃速的测试方法。它可以设置不同的压强变量条件来进行连续的实时燃速测量。叙述了国外超声波燃速测试技术在推进剂稳态燃速特性、非稳态燃速特性以及各种发动机燃速特性研究领域中的应用。评述了超声波燃速测试方法的特点和适用性,并建议国内研究机构开展该项技术的研究工作。     

变燃速发射药的原理与实现方法

根据身管武器内弹道特点,提出了变燃速发射药的概念,论述了基本原理和实现该原理的技术方法。采用内层为高燃速发射药,外层为低燃速发射药。达到变燃速的目的。实验证明,两层结构的变燃速发射药具有所希望的能量释放规律,表现出很好的渐增性燃烧。变燃速发射同时还具有高能量、普遍适应性、高安全性等特点。     

大型固体助推发动机装药无缸浇注技术研究

对发动机装药无缸浇注技术进行了研究.按国内的二次料斗真空花板除气装药工艺,设计了药浆流入真空系统中成形复杂结构药柱的无缸浇注技术,经过小型燃烧室旋转式无缸连续浇注工艺试验、大型发动机药柱无缸浇注工艺演示试验,验证了无缸浇注的技术可行性.提出在大型固体助推发动机装药中采用无缸浇注工艺成型途径.     

Studies on Energetic Compounds Part 27: Kinetics and Mechanism of Thermolysis of Bis(Ethylenediamine)Metal Nitrates and Their Role in the Burning Rate of Solid Propellants

Four bis(ethylenediamine)metal(II) nitrate (BEMN) complexes, i.e. [M(EDA)₂](NO₃)₂, where M=Cu, Co, Ni and Zn, have been prepared and characterized. Thermolysis of these complexes induced by heat and drop‐weight impact has been investigated by TG‐DTG, DTA, explosion delay (D_E), explosion temperature (T_E) and impact sensitivity measurement. The kinetics of early thermolysis reaction prior to fast decomposition have been evaluated. Contracting area (CA, n=2) and contracting cube (CC, n=3) equations were found to give the best fits in isothermal TG data among all tested nine mechanism‐based kinetic models. The values of activation energy (E_a), T_E, D_E and activation energy for explosion (E*) have been found to be quite lower for the copper complex as compared to cobalt, nickel and zinc complexes. A mechanism of thermolysis has also been proposed. All these complexes were found to be insensitive towards impact of 2 kg weight up to the height of 110 cm. These complexes were used as energetic burning rate modifiers in the combustion of hydroxy‐terminated polybutadiene (HTPB)‐ammonium perchlorate (AP) composite solid propellants. A two‐fold increase in burning rate was observed with copper and cobalt complexes at low concentration (2% by wt.). The in situ freshly formed metal oxides with large number of active sites in their crystallites seem to be better additives for combustion of propellants.     

固体推进剂燃速测试中异常数据的判断和处理方法

为了更精准地剔除固体推进剂燃速数据的异常数据,分析了格拉布斯法则和t检验法则,指出了格拉布斯法则的缺陷.通过两种方法对相同的测试数据进行实验,结果表明,t检验法则在保持格拉布斯法则精度的基础上可以剔除格拉布斯法则不能剔除的异常数据.证明t检验法则可以更精确地筛选异常数据,并在t检验法则的基础上提出了一种新的快速收敛的筛...     

基于一维气相稳态反应流的燃速预估软件研究

在一维气相稳态反应流模型的基础上,总结了适用于双基推进剂、改性双基推进剂、复合固体推进剂燃速预估的修正因子,拓宽了燃烧理论模型的适用范围.采用Visual C++和Microsoft Access为开发工具,完成了基于组分化学键结构参数的固体推进剂燃速预估软件(SPRS)编制.该软件基于Windows XP系统,界面友好,使用方便,具有数据更新和信息查询功能.用户不仅能根据推进剂的化学组成(配方)和给定压强计算燃速、压力指数等参数,还可根据给定的燃速和压力指数等调整推进剂配方组成,对缩短固体推进剂研制周期和节约研制成本具有重要意义.     

单螺杆挤出机固体输送段的优化设计

基于正交实验法与Matlab模拟仿真相结合的方法对单螺杆挤出机的固体输送段进行数值模拟,通过多个目标进行优化分析得到最优结果,得到固体输送段的单螺杆几何参数对固体输送速率和固体输送效率的影响,以及最优的螺杆参数组合。结果表明,优化结果不仅有较高的可靠度,而且还能缩短单螺杆的设计周期,可减少研发成本。     

Spray Congealing of Pharmaceuticals: Study on Production of Solid Dispersions Using Box-Behnken Design

This work aimed at evaluating the spray congealing method for the production of microparticles of carbamazepine combined with a polyoxylglyceride carrier. In addition, the influence of the spray congealing conditions on the improvement of drug solubility was investigated using a three-factor, three-level Box-Behnken design. The factors studied were the cooling air flow rate, atomizing pressure, and molten dispersion feed rate. Dependent variables were the yield, solubility, encapsulation efficiency, particle size, water activity, and flow properties. Statistical analysis showed that only the yield was affected by the factors studied. The characteristics of the microparticles were evaluated using X-ray powder diffraction, scanning electron microscopy, differential scanning calorimetry, and hot-stage microscopy. The results showed a spherical morphology and changes in the crystalline state of the drug. The microparticles were obtained with good yields and encapsulation efficiencies, which ranged from 50 to 80% and 99.5 to 112%, respectively. The average size of the microparticles ranged from 17.7 to 39.4 µm, the water activities were always below 0.5, and flowability was good to moderate. Both the solubility and dissolution rate of carbamazepine from the spray congealed microparticles were remarkably improved. The carbamazepine solubility showed a threefold increase and dissolution profile showed a twofold increase after 60 min compared to the raw drug. The Box-Behnken fractional factorial design proved to be a powerful tool to identify the best conditions for the manufacture of solid dispersion microparticles by spray congealing.     

有限元分析应用于轿车轮胎结构设计的优选

应用通用有限元分析软件分析了同一规格,３种不同结构设计的轿车子午线轮胎,得出结构设计对轮胎接地宽度和带来应力分布有较大影响的结论,分析结果可用于结构设计的优选,并把该静态分析用于推测轮胎低速滚动下的情况。     

HDPE焊接三通管件壁厚数值优化设计

输气焊接HDPE三通管道,由于焊接使材料性能下降,并产生应力集中,因此必须对管道连接处增加壁厚.基于对HDPE材料性能和焊接处HDPE材料拉伸强度的试验,对HDPE材料三通管道壁厚进行数值优化设计.有限元模型中采用理想弹塑性和Ramberg-Osgood两种材料本构模型,计算得到管道等应力线以及壁厚优化曲线,对管道设计具有实际意义.     

旋流式喷雾干燥塔热风环与干燥塔通道均流设计优化研究

为提高旋流式喷雾干燥塔内部流场均匀性,应用数值模拟方法对干燥塔热风环与干燥塔通道出口横截面进行优化设计。采用RNGκ-ε模型模拟空气流动。优化设计采用减小热风流量较大的通道出口横截面积的方法来实现,经过优化设计后进入干燥塔的热风体积流量相对标准偏差从11.08%降低到2.18%,达到设计允许偏差要求。