排序方式: 共有34条查询结果,搜索用时 66 毫秒
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O.V. Postylyakov I.B. Belikov N.F. Elansky A.S. Elokhov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2006,37(12):2231-II
To investigate the vast area of Russia, a mobile scientific facility based in a railway carriage was developed. It is capable to perform continues measurements being coupled in a passenger train traveling along railroads. It was first equipped with a spectrometer for remote sensing of ozone and nitrogen dioxide in the atmosphere for the transcontinental observations into the chemistry of the atmosphere-4 expedition performed from February 18 to March 5, 1998. A twilight DOAS method, which was applied for retrieval of the nitrogen dioxide profiles basing on spectral measurements at the visible wavelengths (434–451 nm), is described in the paper. Main features of a new algorithm for retrieval of the ozone profile and total content using the differential structure of the UV spectrum (310–335 nm) are presented. The ozone and nitrogen dioxide contents are obtained and shortly validated against available alternative data. 相似文献
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赵辉 《西安航空技术高等专科学校学报》2006,24(1):24-26
容易产生燃油渗漏的主要部位是飞机燃油箱的结构搭接缝、对接缝、接头部位、紧固件以及放油口和加油口等位置。查找漏源是至关重要的,然后采取相应的措施,修理油箱、紧固螺拴、重涂封胶,以保证航班正点和安全。 相似文献
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燃料分配方式对微燃机燃烧室燃烧性能影响 总被引:1,自引:1,他引:0
提出了一种喷口位置可变采用燃料多点喷射的干式低排放(DLE)微型燃气轮机燃烧室,为了获得值班级与主燃级之间燃料分配方式对燃烧性能的影响,对该燃烧室在不同分配方式下的燃烧性能进行了实验测试与数值模拟。结果表明:燃料喷口位置改变对污染物排放影响不显著;燃料分配方式的改变对温度场和污染物的生成特性有影响,随着两级燃料分配比例的增大,NOx排放量呈现先减少后增加的趋势,存在一个最佳的燃料分配比例使NOx排放最低;燃烧室内存在明显的中心回流区(PRZ),便于点火及火焰传播;热力型NOx的生成量与温度高于1 950 K的区域大小和最高燃气温度有直接关系。所设计的燃烧室在以天然气为燃料的所有工况下NOx排放都可降低到50 mg/m3以下,达到了低污染燃烧室排放标准(小于50 mg/m3)。 相似文献
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民用航空发动机低排放燃烧室技术发展现状及水平 总被引:6,自引:0,他引:6
为了从科学和技术的角度展望民用航空发动机低排放燃烧室技术的发展方向,基于污染物生成机理及控制原理阐述了富油和贫油燃烧的污染排放控制方法,回顾了富油-焠熄-贫油燃烧(RQL)、贫油预混预蒸发燃烧(LPP)和贫油直接喷射燃烧(LDI)3种低污染燃烧技术的发展现状,并分析了新一代民用航空低排放燃烧室技术目前所达到的低污染排放水平。采用贫油燃烧技术的双环预混旋流器燃烧室(TAPS)已经应用于型号并取证,其NOx排放比CAEP/6(Committee on Aviation Environmental Protection/6)标准低50.0%~65.8%,达到了超低排放水平,证明了贫油燃烧的发展潜力。要实现NOx排放比CAEP/6低75.0%以上的超超低排放目标,需要利用燃烧数值模拟和光学诊断等先进工具,对燃烧室内喷雾、混合、流动、燃烧及它们之间的非定常相互作用开展更深入的研究。 相似文献
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Frieda B. Taub 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
To investigate the effect of nitrogen sources on Closed Ecological Systems (CESs), three nitrogen sources (NaNO3, sodium nitrate; NH4Cl, ammonium chloride; and NH4NO3, ammonium nitrate) were each tested in freshwater CESs consisting of a chemically defined medium, three species of green algae (Ankistrodesmus, Scenedesmus, and Selenastrum), the grazer Daphnia magna, and associated microbes, under 12 h light/12 h dark cycles. It had been hypothesized that the development of high pH in earlier CESs was the result of nitrate utilization, and that ammonium might result in acid conditions, while ammonium nitrate might result in more moderate pH. The three nitrogen sources supported similar densities of algae (estimated by in vivo fluorescence) and similar Daphnia populations. The experiments showed that pH levels rapidly increased when grazers were absent or at low abundances irrespective of the nitrogen source. Consequently, it is hypothesized that carbon cycles, rather than nitrogen sources, are responsible for the pH dynamics. Oxygen diurnal (light:dark) cycles tended to come into balance more quickly than pH. It may be more feasible to convert O2 data to energy units (using “oxycalorific” values) than CO2 data since CO2 dynamics may include other chemical reactions than just photosynthesis and respiration. The feasibility of sustaining grazer populations for at least several weeks in small, simple CESs was demonstrated, along with the ability to monitor algae-grazer dynamics, and the recording of O2 and pH measurements. 相似文献
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采用AMESim软件对氮气贮存压力为1.5×10 7 Pa、推力范围为mN级的压电驱动的氮气微推进系统进行建模。研究了氮气填充过程中氮气瓶、减压阀的压力和质量流量瞬态特性。分析了整合喷管的压电比例阀在开机过程中的瞬态工作特性。最后,研究了驱动电压对压电比例阀在开机过程中的阀芯位移和喷管推力瞬态值、阀芯运动和推力响应时间的影响规律。结果显示,当驱动电压为80 V时,阀芯的响应时间和稳定位移分别为 0.64 ms 和3.67 μm。开机后8 ms,喷管推力达到稳定值(0.588 mN)。压电比例阀阀芯的开启响应快速,且驱动电压与喷管推力之间存在良好的线性关系,说明推力可通过改变驱动电压进行mN级的线性调节。 相似文献
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文章结合大型空间环境模拟试验的特点对林德循环和克劳特循环两种液化方法进行改进,提出节流膨胀和涡轮膨胀两种回收方案。计算出它们的较佳运行参数,分析和比较了两个方案的技术性和经济性,为我国空间环境模拟设备冷氮气回收系统研制提供了有益的参考。 相似文献