Three-Dimensional Simulation of Base Bleed Unit with AP/HTPB Propellant in Fast Cook-off Conditions

In this work, a three-dimensional unsteady heat transfer model of base bleed unit with trilobite ammonium perchlorate (AP)/hydroxyl-terminated polybutadiene (HTPB) composite solid propellant is presented to analyze the cook-off characteristics. According to the two-step chemical reaction of AP/HTPB propellant, a small-scale cook-off test is established. A comparison of the experimental and calculated results is made to verify the rationality of the computation model. On this basis, a cook-off numerical simulation of the base bleed unit at the heating rates of 0.33, 0.58 and 0.83 K/s is presented to investigate the ignition and initiation characteristics. The results show that the ignitions occur on the head face of the AP/HTPB propellant and near the internal gas chamber in these conditions. As the heating rate increases, the runaway time decreases and the ignition temperature rises.     

Thermal Safety Study on TEGDN/NG/NC Gun Propellant

The self-accelerating decomposition temperature (T_SADT), critical temperature of thermal explosion (T_b), adiabatic time to explosion (t_TIad), 50% drop height of impact sensitivity (H₅₀), critical temperature of hot spot initiation caused by impact (T_cr,hotspot), safety degree (S_d), critical thermal explosion ambient temperature (T_acr), and thermal explosion probability (P_TE) of the gun propellant composed of triethyleneglycol dinitrate (TEGDN), nitroglycerin (NG), and nitrocellulose (NC) were studied. The results of thermal safety evaluation on the gun propellant were obtained: (1) T₀₀ = 433.4 K, T_SADT = T_e0 = 441.1 K, T_b = T_bp0 = 468.4 K; (2) when E_k = 205.3 × 10³ J mol ^?1 and A_k = 10^20.62 s ^?1, t_TIad = 48.3 s, H₅₀ = 17.93 cm, T_{cr, hotspot} = 634.9 K; for a sphere sample, T_S(T)max  = 369.0K, T_acr = 364.2 K, S_d = 65.03%, P_TE = 34.96%.     

Studies on ballistic parameters of di-butyl phthalate-coated triple base propellant used in large caliber artillery gun ammunition

Triple base propellant (TBP) containing mainly nitrocellulose, nitroglycerine, and nitroguanidine has been manufactured and coated with plasticizer in the present work. The aim was to study ballistics of di-butyl phthalate (DBP)-coated TBP. DBP solution in ethanol containing nitrocellulose dope was used for coating onto the propellant grains. DBP-deterred propellant showed inhibition to burning, resulting in lowering the values of ballistic parameters namely peak pressure (P_max), dP_max, pressure index (α), and burning rate coefficient (β) during closed vessel firing. Increase in percentage of DBP in coating solution led to further decrease in ballistic parameters. Dynamic evaluation of the surface-moderated propellant showed comparatively lower muzzle velocity and chamber pressure for deterred propellant batches without leaving any unburnt particles in gun chamber at subzero temperatures with the lowest possible charge mass. The DBP-coated propellant can be useful in 155-mm artillery gun to achieve higher loading density as it has lower flame temperature and chamber pressure as compared to uncoated propellant which will result in increasing barrel life due to reduction in the barrel erosion.     

基于双孔隙和三孔隙模型的缝洞型储层导电理论研究

在Warren-Root电导模型的基础上,基于电阻网络串并联思想,推导了基质-裂缝、基质-非连通孔洞、裂缝-非连通孔洞等双孔隙储层的电阻率理论模型和基质-裂缝-非连通孔洞三孔隙储层的电阻率理论模型,并与相关理论模型和实验数据进行了对比分析,阐述了裂缝和非连通孔洞对缝洞型储层电阻率的影响。当总孔隙度大于1%时所建立的双孔隙和三孔隙电阻率理论模型可有效地计算100%饱和水的缝洞型储层电阻率;裂缝对缝洞型储层的电阻率起主要作用,微小裂缝的出现可以大大提升储层导通能力;非连通孔洞对电阻率的增大作用较小,地层电阻率因素的增加量小于10%。该电阻率理论模型进一步揭示了缝洞型储层电阻率与孔隙结构的关系,对于定性认识复杂孔隙结构储层导电过程具有指导性作用。     

基于知识库的焊接工艺设计的专家系统

从分析焊接工艺的特点出发,提出了基于知识库的焊接工艺设计的专家系统。文中根据系统要求建立了数据库（DB）;获取专家经验及领域知识建立了知识库（KB）;依据知识层次结构建立了模型库（MB）;这3库一体化形成专家系统（ES）。文中还介绍了多因素综合分析法,讨论了规则表示等问题。     

加热温度对X90钢级热煨弯管组织与性能的影响

为了获得X90钢级弯管的合理热处理工艺,采用Gleeble3500热模拟试验机,研究了高强度X90焊管焊缝和母材在不同加热温度下的组织与性能。试验结果显示,随着加热温度的升高,焊缝先共析铁素体减少,并出现粒状贝氏体组织,硬度上升;焊缝冲击功呈现先升后降趋势,当加热到925℃时,冲击功最低,加热到975℃时冲击功最高,但加热温度超过1 050℃时,针状铁素体板条粗大,夏比冲击功下降。因此得出结论,焊缝最佳的加热温度区间为950~1 025℃。在此温度区间内,母材随着加热温度的增加,块状铁素体逐渐减少,硬度上升,同时原奥氏体晶粒不断长大,夏比冲击功总体变化不大;当加热温度超过1 050℃时,粒状贝氏体晶粒粗化,冲击韧性快速下降。     

相似理论的斜拉索管桥力学特性研究

利用相似理论搭建了斜拉索管桥的模型实验系统,进行了斜拉索管桥的静力学分析实验,同时采用数值模拟的方法对该管桥进行了非线性有限元分析,用模型实验来验证数值模拟结果的可靠性。通过对比斜拉索管桥在空载、集中载荷以及拉索断裂等工况下的实验数据与模拟数据,分析得出模拟数据的最大偏差在11％以内,模拟结果与实验结果吻合性良好,采用的数值模拟方法可以用来解决斜拉索式管桥工程实际问题。     

泡沫沥青冷再生水泥稳定碎石基层力学性能实验室研究

针对泡沫沥青冷再生混合料,对沥青的发泡性能、级配及泡沫沥青冷再生混合料力学性能等进行了研究,并对泡沫沥青冷再生混凝土各性能参数进行了归纳总结,对泡沫沥青冷再生材料的推广应用具有借鉴意义。     

聚丙烯酰胺水溶液粘弹性研究

在45℃下测定了水解度相近(26.4%～27.4%)、分子量不同(7.0×106,1.1×107和1.7×107)的3种商品HPAM水溶液的动态粘弹性参数并讨论了在驱油中的作用。在振荡频率0.1～100s-1范围,浓度1.2g/L的3种聚合物溶液的G′和G″曲线均相交,交点对应的频率随分子量增大而减小,在交点以下G″>G′,而在交点以上G′>G″。对于分子量较高的2种聚合物溶液,在频率1.256s-1时,G′和G″随聚合物浓度的增大(0.2～2.0g/L)而增大;浓度一定时(2.0g/L)随加入的NaCl浓度的增大(0～9.0g/L)而剧烈减小,随加入的表面活性剂SDBS浓度的增大(0～10g/L)而有一定幅度的减小;在温度10～55℃区间测得的2.0g/L聚合物溶液的G′～T和G″～T曲线,在温度～35℃时出现最大值。加入5.0g/LNaOH或NaCl使浓度1.2g/L的最高分子量聚合物溶液的线性粘弹性区间变窄,损耗角增大。图6参1表8。     

基于多级蒸汽机械再压缩热泵的稀N,N-二甲基甲酰胺水溶液蒸馏浓缩工艺

分析了蒸汽机械再压缩(MVR)热泵蒸馏浓缩工艺的特点和适用工况,以稀N,N-二甲基甲酰胺水溶液的浓缩过程为研究对象,提出了三级MVR热泵蒸馏浓缩工艺。采用Aspen Plus化工流程模拟软件中的严格精馏模块和压缩机模块,以能耗最低为目标函数,对三级MVR热泵蒸馏浓缩工艺和三效蒸馏浓缩工艺分别进行了模拟与优化,得到了合适的工艺操作参数。模拟结果表明,与三效蒸馏浓缩工艺相比,三级MVR热泵蒸馏浓缩工艺节能约83.2%,其平均能效比(压缩机制热量与压缩机输入功率的比)为0.834;多级MVR热泵蒸馏浓缩工艺具有较大的经济优势。     

Theoretical Evaluation of Crosslink Density of Chain Extended Polyurethane Networks Based on Hydroxyl Terminated Polybutadiene and Butanediol and Comparison with Experimental Data

Polyurethane networks between hydroxyl terminated polybutadiene (HTPB) and butanediol (BD) were prepared using toluene diisocyanate (TDI) as the curative. HTPB and BD were taken at equivalent ratios viz.: 1:0, 1:1, 1:2, 1:4, and 1:8. Crosslink density (CLD) was theoretically calculated using α-model equations developed by Marsh. CLD for the polyurethane networks was experimentally evaluated from equilibrium swell and stress–strain data. Young’s modulus and Mooney–Rivlin approaches were adopted to calculate CLD from stress–strain data. Experimentally obtained CLD values were enormously higher than theoretical values especially at higher BD/HTPB equivalent ratios. The difference in the theoretical and experimental values for CLD was explained in terms of local crystallization due to the formation of hard segments and hydrogen bonded interactions.     

基于数字岩心技术的页岩储层可压裂性定量评价

页岩的可压裂性评价对页岩储层压裂施工具有重要的指导意义。常规方法基于岩心刻度测井得到弹性参数、矿物含量等信息构建脆性指数,未考虑压裂前后储层的变化特征,在实际应用中效果较差。为克服常规的弹性参数和矿物含量等构建脆性指数无法动态监测压裂效果的缺陷,提出一种基于数字岩心的页岩可压裂性定量评价方法。根据压裂前后的CT扫描图像重构三维数字岩心,应用最小外接长方体技术实现裂缝的自动识别,提出原生裂缝发育指数F_1和力学特性指数F_2分别表征压裂前后储层裂缝的变化情况。在此基础上,采用单因素分析和神经网络方法建立基于测井资料的F_1和F_2模型,直观、定量评价昭通A井页岩储层可压裂性,取得较好的应用效果。     

改性天然高分子水基钻井液的研究与应用

简介了4种对环境无害的固态的水基钻井液处理剂的合成及性能:改性天然高分子类包被剂IND30和降滤失剂NAT20,无萤光白沥青NFA25(部分溶于水、部分溶于油的改性油类物质)及粉状聚合醇PGCS1(EO/PO共聚物)。报道了用膨润土和这4种处理剂配制的各种实验钻井液的组成和性能:基本配方钻井液(钻井液1)、强抑制性钻井液(钻井液2,另加入一种小阳离子页岩抑制剂)、抗盐钙污染钻井液(加入35%NaCl和1?SO4),抗膨润土污染钻井液(加入4%钙膨润土)。这4种钻井液在原配制状态和在120℃、140℃滚动16小时后,各流变参数均在合理范围,API滤失量≤5 2mL,HTHP滤失量≤20mL。某油藏储层钻屑在钻井液1、2中于140℃滚动16小时后,回收率分别为91 2%和96 7%;该储层岩心被原配制和在140℃滚动16小时后的钻井液1、2污染后,渗透率恢复率为88 2%～91 6%。4种处理剂溶液,钻井液1、2及两口井使用的钻井液均无毒,EC50>3×104mg/L。该体系多功能水基钻井液已在塔里木、克拉玛依等油田10余口井钻井中获得成功应用,最长裸眼长度达5324 45m,井眼扩大率仅5%～10%。详细介绍了在LG区块使用的钻井液分井段组成、维护及性能。表4参3。