轻小型太阳能/氢能无人机发展综述

轻小型无人机（UAV）在军民领域都有着广泛的用途，电动无人机由于其振动低、无污染、无排放等优势，已经成为无人机领域的发展热点。为了提高轻小型电动无人机的航时，清洁、高能量密度的太阳能和氢能成为非常可行的技术途径之一。本文总结了轻小型太阳能、氢能无人机的发展历程；梳理了相关的关键技术，并对太阳能、氢能无人机的总体设计方法和能源动力系统的发展进行了较为深入的探讨；最后，展望了该类无人机的发展趋势，并对所面临的挑战进行了预测。     

高度补偿喷管的氢氧热试研究

采用气氧作氧化剂、气氢作燃料, 对具有高度补偿特性的塞式喷管和双钟型喷管进行了点火热试.介绍了气氢/气氧试验系统, 以及试验喷管的结构形式、设计参数和装配照片, 喷管试验件采用耐烧蚀的钨渗铜材料加工, 成功进行了多次短时间点火热试.给出了试验测量参数曲线、点火热试照片和数据结果, 获得了不同高度下塞式喷管和双钟型喷管的热试性能数据, 和当量钟型喷管相比两者都具有较好的高度补偿特性.以推力系数效率为例, 塞式喷管在低空压强比下达到92%-95%, 双钟型喷管低空下为96%-98%, 高空下则都在95%左右.      

超声速燃烧室凹槽动态特性试验研究

为研究超声速燃烧室中凹槽火焰稳定器的流动特性,对来流马赫数2.0条件下各种构型的凹槽流场进行了试验研究。得到了不同几何构型凹槽流场的纹影结果,采用动态压力传感器研究了凹槽流场的频谱特性,计算了凹槽流场自激振荡压力的均方根,并将试验结果和Rossiter经验公式预测结果进行了对比。     

栅格翼尾流中的发卡涡

介绍了在水漕中用氢气泡法显示的斜置蜂窝式栅格翼尾流流态 ,发现在中等迎角下 ,相交翼元的每个交叉处邻近壁面的尾流中 ,有伴随着壁面流动分离而周期性脱落的发卡涡 ,它们相互连接 ,形成“涡链”。还介绍了栅格翼尾流中发卡涡的主要流动特征 ,并对其产生的流动机理作了初步探讨。     

铝锂合金中的氢和氢脆

针对铝锂合金中氢含量甚高的难题，阐述了铝锂合金氢的来源，氢的存在形式及氢对铝锂合金性能和断裂方式的影响。认为制约铝锂会金潜能发挥和应用的主要障碍是合金的冶金质量，而其核心是氢含量控制和氢脆问题，降低氢含量是合金取得实质性突破的关键。提出以真空精炼和固态除氢的途径降低铝锂合金的氢含量，指出液态和固态真空除氢过程中所遇到的主要问题，问题的解决将为新一代高韧铝理合金的研究打下基础。     

氢燃料的特性与应用前景

本文论述了氢作为动力燃料的特性,介绍了氢能利用技术方面的概况。讨论了由烃燃料向氢燃料过渡的几种方式,目前氢燃料存在的问题以及氢能的应用前景。     

One-dimensional numerical investigation on multi-cylinder gasoline engine fueled by micro-emulsions,CNG, and hydrogen in dual fuel mode

This research work is the novel state-of-the-art technology performed on multi-cylinder SI engine fueled compressed natural gas, emulsified fuel, and hydrogen as dual fuel. This work predicts the overall features of performance, combustion, and exhaust emissions of individual fuels based on AVL Boost simulation technology. Three types of alternative fuels have been compared and analyzed. The results show that hydrogen produces 20% more brake power than CNG and 25% more power than micro-emulsion fuel at 1500 r/min, which further increases the brake power of hydrogen, CNG, and micro-emulsions in the range of 25%, 20%, and 15% at higher engine speeds of 2500–4000 r/min, respectively. In addition, the brake-specific fuel consumption is the lowest for 100% hydrogen, followed by CNG 100% and then micro-emulsions at 1500 r/min. At 2500–5000 r/min, there is a significant drop in brake-specific fuel consumption due to a lean mixture at higher engine speeds. The CO, HC, and NO_x emissions significantly improve for hydrogen, CNG, and micro-emulsion fuel. Hydrogen fuel shows zero CO and HC emissions and is the main objective of this research to produce 0% carbon-based emissions with a slight increase in NO_x emissions, and CNG shows 30% lower CO emissions than micro-emulsions and 21.5% less hydrocarbon emissions than micro-emulsion fuel at stoichiometric air/fuel ratio.     

The Mars Odyssey Gamma-Ray Spectrometer Instrument Suite

The Mars Odyssey Gamma-Ray Spectrometer is a suite of three different instruments, a gamma subsystem (GS), a neutron spectrometer, and a high-energy neutron detector, working together to collect data that will permit the mapping of elemental concentrations on the surface of Mars. The instruments are complimentary in that the neutron instruments have greater sensitivity to low amounts of hydrogen, but their signals saturate as the hydrogen content gets high. The hydrogen signal in the GS, on the other hand, does not saturate at high hydrogen contents and is sensitive to small differences in hydrogen content even when hydrogen is very abundant. The hydrogen signal in the neutron instruments and the GS have a different dependence on depth, and thus by combining both data sets we can infer not only the amount of hydrogen, but constrain its distribution with depth. In addition to hydrogen, the GS determines the abundances of several other elements. The instruments, the basis of the technique, and the data processing requirements are described as are some expected applications of the data to scientific problems.     

The extraterrestrial UV-background and the nearby interstellar medium

Recent measurements of the extraterrestrial UV- and EUV-radiation, and the various theoretical approaches used in explaining the measured features of these radiations are reviewed. Whereas the structures and intensities of extraterrestrial EUV-radiation are essentially undetermined up to now, the observations of the extraterrestrial UV-sky give a clear indication of the existence of neutral interstellar hydrogen within the solar system.The effects of solar radiation pressure, and of temporal variations and spatial asymmetries in the solar radiations, on the structure of the extraterrestrial L sky are investigated in detail, and the various attempts to derive interstellar parameters from the interpretation of the measured L intensities are discussed.From these discussions the local interstellar medium is established as a tenuous hot intercloud H i-medium. The amount of its relative motion against the solar system cannot be reliably fixed. Further activities concerning the measurement of extraterrestrial UV- and EUV-radiation features are suggested that may be highly valuable in clarifying the outstanding problems.     

Validation test of 125 Ah advanced design IPV nickel-hydrogenflight cells

An update of validation test results confirming the advanced design nickel-hydrogen cell is presented. An advanced 125 Ah individual pressure vessel (IPV) nickel-hydrogen cell was designed for storing and delivering energy for long-term, low-earth-orbit (LEO) spacecraft missions. The new features of this design are: the use of 26% rather than 31% potassium hydroxide (KOH) electrolyte; a patented catalyzed wall wick; serrated-edge separators to facilitate gaseous oxygen and hydrogen flow within the cell, while maintaining physical contact with the wall wick for electrolyte management; and a floating rather than a fixed stack to accommodate nickel electrode expansion. The resulting improvements include extended cycle life and enhanced thermal, electrolyte, and oxygen management; and accommodation of nickel electrode expansion. Six 125-Ah flight cells based on this design are in the process of being evaluated in a LEO cycle life test     

储氢合金的性质及发展趋势

本文介绍了储氢合金的性质，Ｎｉ－ＭＨ电池原理，以及储氢合金对Ｎｉ－ＭＨ电池所产生的影响，根据目前科学技术的发展以及市场的需求，提出了未来储氢合金及Ｎｉ－ＭＨ电池的发展趋势。     

重整制氢反应器的种类和研制进展

介绍了重整制氢的方法和重整制氢反应器的种类及其特点.重整制氢的方法有3种:水蒸汽重整、部分氧化重整、自热重整.重整制氢反应器有3种:管式反应器、板式反应器和微通道反应器.管式反应器结构简单;板式反应器易于拆装和扩大规模,并且传热效率高,其研究受到了广泛关注;微通道反应器在传热、恒温等性能方面的表现明显优于管式反应器和板式反应器,有较好的发展前景.     

Near-wall topological patterns and flow structures over a simplified Danaus plexippus model

Studies on the high-lift mechanisms of butterfly gliding flights shed light on the design of the micro air vehicles. The flow field around a simplified Danaus plexippus model is investigated using the hydrogen bubble visualization and the Particle Image Velocimetry (PIV) techniques. There are three near-wall topological patterns with different Angles of Attack (AoAs): the separation bubble, the Leading-Edge Vortex (LEV) and the high AoAs flow. For the separation bubble pattern, two saddles and two foci form in the middle of the model. The features of the LEV pattern are the leading-edge separation lines. The topological characteristics of the separation lines are changed by the interaction between the LEV and the Wing-Tip Vortex (WTV). For the high AoAs flow pattern, four unstable foci are found at the forewing and the hindwing respectively. The angle between the trajectory of the WTV and the model increases with increasing AoA even though the slope of the WTV angle versus AoA curve declines at the moderate AoAs.     

X-ray burst sources — A simple two zone model

With the help of a very simple two zone model, we demonstrate the possibility of periodic thermal relaxation (limit cycle) oscillations in the helium burning envelope of accreting neutron stars. Physically reasonable model parameters can be chosen which yield agreement with the observed features of x-ray bursts and we suggest that this limit cycle is operative in neutron stars which have an accretion rate in a specific range. For hydrogen burning a similar cycle is possible, but it operates at such high temperatures that an unrealistically large accretion rate would be required.     

Role of hydrogen in the dissociation of CH4 on different graphene by DFT study

The effect of hydrogen on the growth mechanism of pyrocarbon has attracted much attention. The influence of hydrogen on the dissociation from CH4to C2H2on pristine graphene,N-doped graphene and vacancy graphene have been investigated by using density functional theory.There are two kinds of heterogeneous reaction pathways when the hydrogen is involved, i.e., dehydrogenation reactions and H-abstraction reactions. The transition state calculations were performed to acquire the reaction pathways on...     

利用TDS研究二次硬化钢中氢的扩散行为

利用升温脱氢分析装置(TDS)和慢速拉伸试验方法(SSRT)研究了一种二次硬化钢中氢的扩散行为及其对塑性的影响。结果表明,由于二次硬化实验钢中存在大量细小碳化物,氢的扩散系数约为3.42×10-8cm2.s-1,明显低于通常淬火回火马氏体钢。TDS分析发现,实验钢中存在两个氢逸出峰,激活能分别为20.2kJ.mol-1和24.6kJ.mol-1,由晶界、位错等弱氢陷阱引起。拉伸试样的断面收缩率随氢质量分数的增加先线性下降,氢质量分数每增加1×10-4%断面收缩率下降约12%;当氢质量分数达到5×10-4%时,断面收缩率低于10%,断口呈沿晶状。     

氢处理对钛合金组织性能的影响及其机理

总结了钛合金的氢处理工艺方法，综述了氢在钛合金中的基本效应，以及氢对钛合金的组织结构和力学性能的影响规律及其机理。     

横向脉冲喷流超声速燃烧流场数值模拟与分析

为了研究横向脉冲喷流对燃烧室流场结构及燃烧特性的影响,对带后台阶的超燃冲压发动机燃烧室横向氢气喷流超声速燃烧流场进行了数值模拟。采用有限体积法求解多组元Navier-Stokes (NS)方程,分别对定常喷流与两种脉冲喷流超声速燃烧流场进行了数值计算,对比分析了三种氢气喷注方案下的流场结构、氢气掺混燃烧特性及燃烧室总压恢复特性。研究表明:脉冲干扰仅对燃烧室内局部流场产生周期性影响,且有利于氢气的横向扩散;采用与定常喷注喷流参数相同的脉冲喷注方案时,可在脉冲干扰区内保持氢气掺混量与定常喷注基本相同,氢气燃烧量与总压恢复系数整体上与定常喷注基本一致;采用特征时间内喷出氢气质量流量与定常喷注相同的脉冲喷注方案时,在燃烧室出口处氢气掺混量和燃烧量较定常喷注分别提高了21.94%和32.24%,总压恢复系数仅减小4.17%。采用脉冲喷注方案增加了燃料与空气接触面面积,对燃料掺混及燃烧起促进作用。     

高混合比火炬式电点火器试验研究

介绍了低温高混合比火炬式电点火技术的初步研究进展,包括有关的设计参数和试验情况。该点火器用电火花塞作为激励能源,氢氧推进剂通过一个位于头部的同轴式喷嘴进入点火室,大部分液氢用作冷却剂通过排放冷却方式冷却点火室。累计５次共５０ｓ的热试车表明,高混合比火炬式电点火器能实现可靠的低温点火,并具有较广的工况和混合比变化范围。     

The Hydrogen Exospheric Density Profile Measured with ASPERA-3/NPD

We have evaluated the Lyman-α limb emission from the exospheric hydrogen of Mars measured by the neutral particle detector of the ASPERA-3 instrument on Mars Express in 2004 at low solar activity (solar activity index = 42, F_10.7=100). We derive estimates for the hydrogen exobase density, n _H = 10¹⁰ m^?3, and for the apparent temperature, T > 600 K. We conclude that the limb emission measurement is dominated by a hydrogen component that is considerably hotter than the bulk temperature at the exobase. The derived values for the exosphere density and temperature are compared with similar measurements done by the Mariner space probes in the 1969. The values found with Mars Express and Mariner data are brought in a broader context of exosphere models including the possibility of having two hydrogen components in the Martian exosphere. The present observation of the Martian hydrogen exosphere is the first one at high altitudes during low solar activity, and shows that for low solar activity exospheric densities are not higher than for high solar activity.