新型燃烧稳定剂对浇铸RDX-CMDB推进剂燃烧性能的影响

为选择理想的新型燃烧稳定剂,研究了WB、WC、ZrB2、ZrO2、SiC和BN对浇铸RDX-CMDB推进剂燃速和燃速压力指数的影响。结果表明,6种材料都能降低推进剂的燃速,但降低幅度各有差异;ZrB2、ZrO2和SiC对推进剂燃速的降低作用随其粒度的减小而增大;WB和WC在一定含量下可以降低推进剂18～20.5MPa下的燃速压力指数;只有BN使推进剂的燃烧平台效应消失。     

燃烧稳定剂对RDX-CMDB推进剂热分解特性的影响

用高压DSC和Ⅱ型钨铼微热电偶实验研究了5种燃烧稳定剂(Al2O3、ZrB2、ZrO2、SiC、WC)对RDX-CMDB推进剂的热分解特性及燃烧波温度分布的影响.结果表明,随着压力的升高,RDX-CMDB推进剂的两个特征分解峰温降低,分解热增加.相同压力下,5种燃烧稳定剂对两个特征峰温的影响不大,但对分解热影响显著,其影响程度为ZrO2和WC最大(甚至能将5MPa下的分解热提高28％以上),Al2O3次之,ZrB2、SiC最小;不同燃烧稳定剂对RDX-CMDB推进剂燃烧的作用区间不同,ZrO2和WC主要作用于固相反应区及嘶嘶区,Al2O3则作用于气相区,使作用区域的放热量及温度梯度明显提高.     

铜盐对RDX-CMDB推进剂燃烧性能的影响

研究了6种铜盐(DBC、CNI、NT-Cu、B-Cu、S-Cu、A-Cu)以及铜盐/炭黑复配体系对RDX-CMDB推进剂燃烧性能的影响,用扫描电镜和元素分析测试了推进剂的熄火表面.结果表明,铜盐可降低RDX-CMDB推进剂在16～22 MPa的压强指数;在10～22 MPa,铜盐和铜/炭黑混合物对RDX-CMDB推进剂燃烧特性的影响不显著.铜盐催化剂以及铜盐和炭黑复配催化剂对推进剂的燃烧反应有一定的促进作用.     

利用燃烧稳定剂调节燃速的研究

在不同燃烧稳定剂及常用稳定剂 Al2 O3不同粒度对燃烧速度影响研究的基础上 ,进一步探索了利用不同稳定剂以及 Al2 O3不同粒度复合来调节推进剂燃速的可能性     

无烟固体推进剂燃烧稳定剂最佳粒度的实验研究

本文对无烟固体推进剂中Al_2O_3燃烧稳定剂的最佳微粒尺寸进行了理论计算及实验研究。对声振频率1000、1500、2000Hz的发动机用计算机计算出抑制声不稳定燃烧的最佳微粒直径分别为2.8、2.3和2.0μm。同时对含不同微粒直径的三种推进剂进行了T形发动机试验,其响应函数在0.41～1.69之间,说明微粒直径在2.5μm左右的Al_2O_3可有效地抑制高频不稳定燃烧。实验结果与理论计算完全一致。     

无烟固体推进剂燃烧稳定剂最佳粒度的实验研究

本文对无烟固体推进剂中Al_2O_3燃烧稳定剂的最佳微粒尺寸进行了理论计算及实验研究。对声振频率1000、1500、2000Hz的发动机用计算机计算出抑制声不稳定燃烧的最佳微粒直径分别为2.8、2.3和2.0μm。同时对食不同微粒直径的三种推进剂进行了T形发动机试验,其响应函数在0.41～1.69之间,说明微粒直径在2.5μm左右的Al_2O_3可有效地抑制高频不稳定燃烧。实验结果与理论计算完全一致。     

含高氮化合物的CMDB推进剂的燃烧特性

以3,6-双(1-氢-1,2,3,4-四唑-5-氨基)-1,2,4,5-四嗪(BTATz)和2-硝亚胺基-5-硝基-六氢化-1,3,5-三嗪(NNHT)为含能添加剂应用于含RDX或HNIW的CMDB推进剂中,考察了BTATz和NNHT对推进剂燃速、火焰和熄火表面形貌的影响。结果表明,BTATz能大大提高推进剂的燃速,而NNHT有助于推进剂产生平台燃烧,分别完全取代RDX后,推进剂的燃烧显现出不同于RDX-CMDB推进剂的独特的暗区形貌,在暗区内部存在由燃烧表面发出的发散火焰束,这主要得益于BTATz和NNHT自身高燃速特性及其燃烧时不存在如RDX的熔融过程;含与不含高氮化合物的RDX-CMDB推进剂火焰形貌类似,熔融态的RDX妨碍了燃烧表面高热碳粒的生成,较少的高热碳粒不利于RDX-CMDB推进剂燃速的提升;常用的铅-铜-碳催化体系对于推进剂的燃烧同样也具有理想的调节作用,在该催化体系与NNHT的协同作用下,8~22MPa范围内NNHT-RDX-CMDB推进剂压强指数降至0.19,降幅达76%,NNHT-HNIW-CMDB推进剂压强指数降至0.42,降幅达50.6%;该催化体系对BTATz、NNHT、HNIW不敏感,催化体系本质上还是主要作用于双基基体,发生在燃烧表面及近燃面的凝/气相区,使得燃烧表面结构发生明显改变,CMDB推进剂燃烧性能得以改善。     

RDX-CMDB推进剂燃速温度敏感系数的实验研究

为了揭示RDX-CMDB推进剂中各常见组分对其燃速温度敏感系数的影响规律,制备了一系列含RDX、铝粉及燃烧催化剂的CMDB推进剂样品。采用氮气靶线法测得其在2~14MPa下的燃速温度敏感系数(σp)。讨论了RDX含量、铝粉、燃烧催化剂对RDX-CMDB推进剂燃速温度敏感系数的影响。结果表明,提高工作压强、增加RDX含量、添加燃烧催化剂均有助于降低RDX-CMDB推进剂在一定初始条件下的燃速温度敏感系数。配方中引入铝粉后可降低中低压下RDX-CMDB推进剂的燃速温度敏感系数,且燃速温度敏感系数几乎不随压强变化而变化。选用含邻苯二甲酸铅和没食子酸铋锆作燃烧催化剂,均可在2~10MPa下降低RDX-CMDB推进剂的燃速压强指数,同时降低燃速温度敏感系数。     

纳米复合物PbO·SnO2的制备及对双基和RDX-CMDB推进剂燃烧性能的影响

以Pb(NO3)2、SnCl4·5H2O和NaOH为原料,采用室温固相化学反应法制备纳米复合物PbO·SnO2.用X-射线粉末衍射(XRD)、透射电镜(TEM)、傅里叶变换红外光谱仪(FT-IR)和扫描电镜能谱(SEM-EDS)对纳米复合物PbO·SnO2的组成、大小、形貌进行表征.研究了纳米复合物PbO· SnO2对双基和RDX-CMDB推进剂燃烧性能的影响.结果表明,纳米复合物PbO·SnO2的平均粒径约为40～60 nm,在2～20 MPa压力区,能明显提高双基推进剂的燃速,在10～20MPa的压力指数为0.257.在2～20 MPa压力区,该纳米复合物使RDX-CMDB推进剂的燃速有所提高,与炭黑复合使用时,其催化效率进一步提高.     

宽带CARS在诊断固体推进剂燃烧场中的应用

为了测量固体推进剂燃烧场温度和氮气组分的浓度,建立了10 Hz重复频率运转的宽带CARS实验系统.结果表明,氮气CARS谱测量温度的相对不确定度优于4%;在较低浓度范围内,测量组分浓度的相对不确定度优于5%.采用宽带CARS技术测量了常压和2 MPa背景压力下固体推进剂燃烧场,获得了较高信噪比的单次脉冲氮气CARS实验谱,用CARS理论计算软件拟合CARS实验谱给出了固体推进剂瞬态燃烧场温度和氮气浓度随高度的分布.     

Effect of CO Combustion Promoters on Combustion Air Partition in FCC under Nearly Complete Combustion

With CO combustion promoters, the role of combustion air flow rate for concerns of economics and control is important. The combustion air is conceptually divided to three parts：the air consumed by coke burning, the air consumed by CO combustion and the air unreacted. A mathematical model of a fluid catalytic cracking （FCC） unit, which includes a quantitative correlation of CO heterogeneous combustion and the amount of CO combustion promoters, is introduced to investigate the effects of promoters on the three parts of combustion air. The results show that the air consumed by coke burning is almost linear to combustion air flow rate, while the air consumed by CO combustion promoters tends to saturate as combustion air flow rate increases, indicating that higher air flow rate can only be used as a manipulated variable to control the oxygen content for an economic concern.     

Combustion limits of liquid monofuels

A mathematical model for steady-state nonadiabatic waves of filtration combustion of liquid monofuels in narrow tubes is proposed. Using this model, it is shown that combustion in this system can proceed in two regimes with different dominant mechanisms of heat transfer from combustion products to the preflame zone. The nature and parametric dependences of the limits of both regimes are analyzed. Calculations using the model are in good agreement with experimental data on the combustion of liquid hydrazine in narrow tubes. __________ Translated from Fizika Goreniya i Vzryva, Vol. 45, No. 2, pp. 29–39, March–April, 2008.     

Combustion characteristics and kinetics of bio-oil

The combustion characteristics of bio-oils derived from rice husk and corn were studied by thermogravimetry analysis. According to the thermo-gravimetry (TG), differential thermogravimetry (DTG) and differential thermal analysis (DTA) curves of bio-oils in air and nitrogen atmosphere, we analyzed the combustion characteristics of different kinds of bio-oils in different atmospheres and worked out the combustion kinetics parameters of the bio-oil, providing reliable base data for the burning of bio-oil. The thermogravimetry indicated that the combustion process of bio-oil was divided into three stages. At the same time, the combustion process can be described by different order reaction models, and with the method of Coats-Redfern, the activation energy and frequency factor of different kinds of bio-oils were obtained.     

Filtration Combustion of an Energetic Material in a Cocurrent Flow of Its Combustion Products. Critical Combustion Conditions

The paper reports results of a numerical calculation using the threetemperature model developed previously by the authors. In addition to the temperature difference between the gas and the solid phase (skeleton), the model approximately takes into account the temperature distribution in skeleton elements. It is shown that quenching is possible (after burnout of part of the charge) with variation in a number of input parameters: the thermal conductivity of the charge, the ignition temperature, the weight of the igniter, the initial temperature, the porosity of the charge, and the local rate of its decomposition.     

Transition Processes in Filtration Gas Combustion

The behavior of gas filtration combustion waves in the lowvelocity regime has been studied experimentally with variation in the parameters of the gas flow and porous medium. It is shown that in transition processes there may be quenching or formation of a stable combustionwave structure that does not correspond to the initial or final conditions. A nontrivial type of transition process accompanied by spatial transfer of the combustion zone is found.     

全氧燃烧玻璃熔窑氧气耗量和燃烧产物量计算

计算了玻璃熔窑采用全氧燃烧时,燃天然气和燃重油2种燃料分别需要的理论氧气量和产生的理论烟气量。并以600 t/d浮法玻璃熔窑为例,进行了天然气和重油2种燃料在使用不同纯度氧气情况下,全氧燃烧所需要的氧气量和产生的烟气量的设计计算。     

加气型煤的燃烧性能的初步研究

笔者通过对型煤内部加气,使型煤的比表面积显著提高,使氧气的扩散状况得以改善,进而影响型煤的燃烧特性。通过加气型煤非加气型煤的对比燃烧,结果表明加气型煤可有效提高型煤的燃烧速度。     

预混富氧燃烧火焰特性的实验研究

对预混富氧燃烧的火焰特性进行实验研究,结果表明:富氧浓度在21%～30%的范围内变化时,随着氧含量的增加,燃烧反应速率和火焰传播速度逐渐增加,进而引起燃烧区的缩小和温度梯度的增加。并且火焰高温区逐渐缩小,最高火焰温度逐渐增高,并且最高温度点向烧嘴口方向移动。     

R&D Needs and Opportunities in Pulse Combustion and Pulse Combustion Drying

This short communication attempts to summarize briefly the authors’ opinions on R&D needs and opportunities for basic as well as applied research in pulse combustion and pulse combustion drying. It is not all-inclusive. Only minimal citations are made to relevant literature as readers interested in pro-actively pursuing this area can locate it reasonably easily. The objective in presenting this verview is to encourage new researchers in this fascinating and challenging field.