固体火箭推进剂激光分解测试方法的研究

本文是探索应用脉冲激光技术米研究固体火箭推进剂固相高速分解反应动力学的可能性。国内外目前研究推进剂的固相分解反应，大多使用DTA、DSC等热分析仪，这与推进剂燃烧时表面的升温速率相差甚远。脉冲激光则可以模拟燃烧时高的升温速率。另外脉冲激光瞬间使推进剂分解还可减少气体产物对固相反应的影响，为分别研究固相反应和气固反应提供了可能，从而为深入研究推进剂的燃烧机理提供一种新的有效的技术手段。     

含CL-20改性双基推进剂激光点火特性

采用CO2激光点火方法,研究了含六硝基六氮杂异戊兹烷(CL-20)改性双基(CMDB)推进剂在不同功率密度作用下的点火特性,探讨了Al粉含量和燃烧催化剂对该类推进剂激光点火性能的影响。实验结果表明,在激光功率密度25.5~127.0 W/cm2范围内,不含催化剂的CL-20-CMDB推进剂点火延迟时间随功率密度增加而递减,且点火延迟时间变化逐渐减缓,点火均首先在推进剂表面产生;而含有催化剂推进剂试样的点火延迟时间和点火过程则与功率密度密切相关:在高激光功率密度时,含催化剂的推进剂点火没有发生在推进剂表面,而是在试样表面的气相中,且点火延迟时间增加。Al粉含量对其点火延迟的影响在低激光功率密度时较大,随着功率密度增加影响减弱。     

固体推进剂燃烧驱动连续波CO_2气动激光工作特性的数值计算

配合所建立的固体推进剂燃烧驱动ＣＯ２气动激光实验系统，对固体推进剂燃气与高压空气的掺混特性和该种气动激光的工作特性进行了数值模拟计算，有助于获得较为理想的激光工作介质和较高的激光功率输出。     

二茂铁基复合推进剂红外/紫外低特征信号应用研究

针对精确制导武器隐身性能的需要,首先利用模拟的火箭发动机喷口结构测试了HTPB复合推进剂的红外和紫外特征信号,然后分析了二茂铁作为一种消光材料对HTPB复合推进剂火焰在红外波段和紫外波段的辐射信号衰减能力。同时,测试了二茂铁消光材料对火箭发动机的喷口温度的影响。结果表明,利用硝酸钾、硫和酚醛树脂为基础的烟火药配方提供初始能量,促使二茂铁快速汽化,并在推进剂火焰外形成薄层作为消光材料,对红外波段和紫外波段具有明显的遮蔽吸收作用,衰减率可以达到50%以上。得出二茂铁含量为30%时在710~3 500 cm-1波段,对于HTPB复合推进剂的红外辐射衰减效果最好;含量高于50%时对于HTPB复合推进剂的2 400~3 500 cm-1波段的红外辐射强度有所增加。     

点目标的红外辐射特性测量方法

首先给出了红外辐射特性测量的基本原理,对于点目标,由于光学系统的衍射作用,经过光学系统成像为一个弥散斑,由于弥散的原因,点目标的辐射特性测量精度一般都非常低,针对这种情况,提出了一种基于辐射能量守恒的点目标辐射特性测量优化算法,给出了算法的具体原理和实现过程;最后,为了验证算法的有效性,在实验室里利用平行光管和点目标模拟装置进行了点目标辐射特性测量实验,并对试验结果进行了系统分析,结果表明,经过优化算法后,点目标的辐射测量精度优于10%,表明点目标辐射特性测量优化算法在实际应用中有很广泛的前景.     

激光对固体推进剂点火形成的二次燃烧现象

利用反应性光声技术检测了Ｎｄ３＋：ＹＡＧ脉冲激光对固体推进剂点火的全过程。检测结果表明除激光作用时形成的一次燃烧外还存在非光支持的二次燃烧。     

利用傅里叶变换红外光谱仪测量固体推进剂的燃烧温度

利用布鲁克公司生产的OPAG 33型傅里叶变换红外光谱仪(Fourier Transform Infrared Spectrometer, FTIR)对固体推进剂燃烧火焰的温度进行了研究。在仪器的分辨率为4 cm-1、测试距离为20 m的条件下,实时测得了高能硝酸酯增塑聚醚(Nitrate Ester Plasticized Polyether Propellant, NEPE)固体推进剂燃烧火焰的红外发射光谱图。利用燃烧产物中HCl气体分子的发射光谱精细结构谱线计算了NEPE固体推进剂羽流的温度。实验结果表明,利用被动式遥感FTIR光谱仪可对固体推进剂的燃烧温度进行快速实时的非接触式测量,是一种有效的研究手段。     

关于红外加热技术及其应用的讨论(六) 红外涂料增加辐射作用的验证

红外涂料究竟能否增加辐射作用,在这个问题上有两种截然不同的学术观点:肯定者认为,加热器由于涂复了红外涂料而增大了比辐射率,从而也就增加了红外辐射能。否定者认为,当比辐射率增大时,加热器表面的温度却降低了,因此辐射能并未得到增加,由此得出结论:有没有涂料都一样。针对上述观点,笔者进行了能量守恒计算和实验测量,结果表明,前者的观点是正确的,即在加热功率不变的条件下,由于比辐射率增大,虽然表面温度降低,但红外辐射能仍然增加,这就是说,红外涂料是能够增加辐射作用的。     

基于可达辐射能的目标表面辐射传递系数计算方法

为了便于在红外成像仿真中对目标表面温度场进行计算,提出了一种基于可达辐射能的目标表面辐射传递系数计算方法。分别用公式法、蒙特卡洛法和可达辐射能计算法计算了两两垂直表面和两两平行表面模型间的辐射传递系数,并进行了仿真验证。结果表明,该可达辐射能计算方法在确保计算精度满足要求的同时,在计算效率上相对于公式法和蒙特卡洛法都有较大提高。     

透射式红外光学系统的太阳杂散辐射分析

杂散辐射可以定义为经过非正常成像光路进入到接收器中的能量。杂散辐射会降低光学系统的图像对比度和信噪比,严重时杂散辐射的能量会直接将目标能量湮没,严重影响红外光学系统正常工作。本文分析了透射式红外光学系统的杂散辐射特性,设计了物镜筒的消光螺纹和表面处理方式等抑制措施。通过点源透过率曲线分析了抑制措施的作用,并分析了消光螺纹自身辐射对光学系统的影响。最终通过对比成像实验验证,结果表明,消光螺纹对轴外的杂散辐射有明显的抑制作用;同时消光螺纹的自身辐射能量不会引入新的干扰源。     

关于隧道二极管电路

隧道二极管的伏安特性是一条“N”形的曲线，含有隧道二极管的电路是一种非线性电路。研究非线性电路的一种有效方法是分段线性化法,它的特点是把非线性的求解过程分成几个线性区段，对每一个线性区段再应用线性电路的分析方法。本文完整地阐述了分段线性化法的步骤，对如何建立线性化后的方程，进行了较详细的讨论，并在每一个线性区段，建立求解工作点的一组线性方程。最后求解这些方程，它们的有效解就是隧道二极管电路实际的工作点。     

圆柱导体电磁散射问题分析

利用矩量法对圆柱导体电磁散射特性进行了研究.基于伽略金法,采用分域基函数展开模式,得出了圆柱导体的电磁散射方向图,并对圆柱体直径和入射波波长不同比例情况下的散射情况进行了研究.文中还用MATLAB给出了圆柱体电磁散射的精确计算结果.     

Multifield local hyperthermia as a method for heating deeply located neck tissues

Distribution of the thermal field in neck tissues in local SHF-hyperthermia is studied. The two-field method of irradiation permits a uniform heating of more deeply located layers of the tissue due to summation of the radiant energy. So, the contact method of irradiation using "Luch-2" and "Luch-3" sets permits elevating the temperature inside the larynx up to 41-41.5 degrees C and maintaining it under given conditions for 25-30 min, but the heat loading on the skin and subcutaneous fat remains high. When using noncontact irradiators and "Parus" set the deeply located neck tissues are heated to 42-43 degrees C, the temperature of surface layers not exceeding 41-42 degrees C. This temperature rate is possible to be maintained for 25 min; its prolongation induces a sharp rise in the temperature of surface layers. Long-term SHF-hyperthermia of deeply located neck tumours necessitates cooling of the integument surface.     

星载荷热控制辐冷板激光致热计算分析

卫星的温度变化直接影响着电子器件的工作性能,为了研究辐冷板的温升效应对电子器件温度的影响,通过分析辐冷板的散热机理和辐冷板工作特性,采用有限元分析软件,对简化后的辐冷板模型进行了激光辐照热效应计算分析。以脉冲激光作为辐射源,对辐冷板进行照射,通过对其表面温度场进行数值模拟,得到了在脉冲激光照射下的瞬态温度场分布,并对模拟结果进行了分析和研究。发现电子器件在没有散热的情况下温度将升高64.5 K,在最大工作状态时激光的照射将严重影响热管的工作性能,而且热管的非正常工作将使电子器件温度升高,影响电子器件正常运行,为星上温度影响电子器件性能实验奠定了理论基础。     

Moment-method determination of the surface currents and fields radiated by rectangular microstrip patch-antennas

A quantitative solution is presented of the surface currents and the corresponding fields generated in free space by electrically thin microstrip patch-antennas of rectangular configuration. Use is made of a versatile analytical tool known as the method of moments, in which the surface current density is approximated by a series expansion involving piece wise linear basis functions and weighted superposition coefficients which are to be determined. It is shown that when the governing integro-diflerential equations are reformulated in matrix form involving generalized network parameters, the desired current distribution emerges in a simple compact form. A remarkable feature of the result of the present analysis is the fact that the field induced in the substrate is due to a finite charge distribution rather than the previously implied phenomenon, viz. the influence of an infinite charge distribution. Indeed, the charge distribution responsible is directly derivable from the time-harmonic continuity equation. All numerical results displayed are based on the use of plane-wave irradiation and the paper includes a discussion of certain practical feed arrangements as well as some practical applications. Results are presented in graphical forms within the frequency limits 1157-1237 MHz for two different sizes of the conducting patch.     

模拟电子电路故障的检测技巧

模拟电子设备的使用过程中,电路常常会出现故障,对于故障的分析与判断,就是确定故障实际发生的具体功能模块,进一步核实有关故障信息,找出有故障的功能模块。     

Charge storage by irradiation with UV light in non-biased MNOS structures

Charge storage in non-biased MNOS (Metal-Nitride-Oxide-Semiconductor) structures effected by irradiation with UV light has been investigated. The electrons generated by internal photoemission at the Si surface are trapped at the SiO₂Si₃N₄-interface and inside the Si₃N₄. The resulting charge storage in the insulator can be determined by capacitance technique. The observed positive voltage shift in C-V-characteristics depends on photon energy as well as on radiant exposure. The charge storage occurs in three stpes which can be related to various types of traps. The charged structure can partially be discharged by irradiation with light of less energy than needed for the storage process.     

Characterization of radiant emitters used in food processing.

Radiant emissions from short, medium, and long wavelength thermal radiant emitter systems typically used for food processing applications were quantified. Measurements included heat flux intensity, emitter surface temperature, and spectral wavelength distribution. Heat flux measurements were found highly dependent on the incident angle and the distance from the emitter facing. The maximum flux measured was 5.4 W/cm2. Emitter surface temperature measurements showed that short wavelength radiant systems had the highest surface temperature and greatest thermal efficiency. The emitter spectral distributions showed that radiant emitter systems had large amounts of far infrared energy emission greater than 3 microm when compared to theoretical blackbody curves. The longer wavelength energy would likely cause increased surface heating for most high moisture content food materials.