Results of solar observations by the CORONAS-F payload

The CORONAS-F mission experiments and results have been reviewed. The observations with the DIFOS multi-channel photometer in a broad spectral range from 350 to 1500 nm have revealed the dependence of the relative amplitudes of p-modes of the global solar oscillations on the wavelength that agrees perfectly well with the earlier data obtained in a narrower spectral ranges. The SPIRIT EUV observations have enabled the study of various manifestations of solar activity and high-temperature events on the Sun. The data from the X-ray spectrometer RESIK, gamma spectrometer HELICON, flare spectrometer IRIS, amplitude–temporal spectrometer AVS-F, and X-ray spectrometer RPS-1 have been used to analyze the X- and gamma-ray emission from solar flares and for diagnostics of the flaring plasma. The absolute and relative content of various elements (such as potassium, argon, and sulfur) of solar plasma in flares has been determined for the first time with the X-ray spectrometer RESIK. The Solar Cosmic Ray Complex monitored the solar flare effects in the Earth’s environment. The UV emission variations recorded during solar flares in the vicinity of the 120-nm wavelength have been analyzed and the amplitude of relative variations has been determined.     

典型工况下低排放燃烧室的压力振荡特性

为了研究低排放燃烧室在典型工况下的压力振荡特性,针对模型燃烧室进行了燃烧自激振荡特性试验.在试验中测量了采用贫油预混预蒸发(LPP)燃烧技术的低排放燃烧室在典型工况下的压力振荡频率和幅值,在燃烧室进口压力为1.10～2.77MPa、燃烧室进口温度为656～845 K、燃烧室压降为3.41％～4.35％范围内,分析了燃油粒径变化对振荡特性的影响.分析结果表明:局部当量比脉动是引发燃烧不稳定的因素之一.通过计算燃油二次雾化状态下的液滴最大粒径,发现燃油液滴粒径的变化对主燃级出口处的局部当量比脉动有直接影响,从而引起燃烧室压力振荡幅值和频率的变化.     

平板式预膜喷嘴初次雾化特性试验

为深入了解平板式预膜喷嘴初次雾化特性,试验研究不同进口条件对平板式预膜喷嘴初次雾化特性的影响规律。试验采用了背光照明和片状激光照明相结合的高频拍摄手段分别获得液膜俯视和侧视破碎形态,同时运用本征正交分解(POD)法和液膜边缘定位等分析方法进行光学图像结果后处理,获得表征平板式预膜喷嘴初次雾化特性三个物理量:液膜波动频率、破碎距离和横向不稳定波长。试验结果表明:①通过分析侧视和俯视破碎形态,平板式预膜喷嘴液膜破碎形态可分为三类:末端破碎、波浪脱落和表面剥离,进口韦伯数对预膜喷嘴破碎形态的影响占主导地位;②把POD法和液膜边缘定位方法等相结合方法应用到高频非接触光学喷嘴雾化图像的后处理分析中,是一种非常有效的数据后处理方法;③液膜初次雾化特性主要受到进口韦伯数和气液动量比的影响,破碎距离和横向不稳定波长都随进口韦伯数的增加而降低,液膜表面不稳定波动频率随进口韦伯数的增加而增加,所获得的经验关系式与试验数据吻合较好。所获得的进口参数对液膜破碎形态和雾化特性的影响规律为喷嘴后续优化设计提供了依据。     

弱旋流喷嘴的污染排放和燃烧稳定性分析

基于弱旋流喷嘴(LSI)的弱旋流燃烧技术具有极低的NOx污染排放能力.分析了弱旋流燃烧的稳定燃烧和降低污染排放的原理,发现其特殊的流动形式及其与湍流火焰传播的匹配是决定其燃烧稳定性和污染排放的主要因素.而弱旋流喷嘴的旋流叶片角度、直径比和流量比等关键参数会影响LSI的下游流动特征,进而影响其燃烧性能.燃料对LSI燃烧稳定性和污染排放的影响主要是通过火焰传播速度和绝热火焰温度发挥作用.为了将液体燃料应用于LSI,目前主要采用了预混预蒸发的方式,试验结果表明:其NOx排放可比采用常规强旋流喷嘴的燃烧室降低10%~60%,但存在自燃和回火的风险.而LSI喷雾燃烧的方式,则需要针对弱旋流液雾燃烧开展更深入的基础研究.只有解决了液体燃料的LSI应用问题,才能发展出不同于传统强旋流燃烧的新一代航空发动机超低排放燃烧室.      

不同钝体宽度下的驻涡燃烧室排放试验

为了研究空气流量分配对驻涡燃烧室对排放特性的影响,了解对驻涡燃烧室内污染物生成的过程及其影响因素,设计了一个能够改变中心钝体宽度、仅凹腔供油的驻涡燃烧室.在常压下对该驻涡燃烧室进行了排放特性试验,进口温度保持200℃.试验中,燃烧室进口马赫数为0.15~0.3.影响排放的因素主要包括雾化质量、凹腔当量比以及与进口马赫数相关的驻留时间等.总体来说雾化质量、凹腔当量比的提高对降低CO和HC的排放是有利的,但是这会使NOx排放增加.在低凹腔当量比时,CO排放曲线变化下降比较平缓,甚至出现上升趋势,而HC排放曲线比较陡峭.这是由于HC的消耗速度比CO消耗速度快,随着凹腔当量比的增加,供油压力提高,燃油雾化粒径变小,燃油蒸发时间缩短,使HC排放快速减少,中间产物CO大量产生而来不及消耗.凹腔当量比进一步上升时,由于燃烧温度的提高,使得CO排放快速减少.在燃烧室内燃烧过程中,NOx的形成和消耗是非常复杂的过程,目前只能作一些定性的分析,而CO和HC的反应过程相对简单.通过对不同钝体槽宽下,具有相似凹腔前壁流量的工况的比较,发现CO和HC的形成主要受凹腔内工作状况影响,而NOx的形成过程更复杂,主流也对其产生着重要的影响.      

大型客车柴油燃料生命周期分析

以实施第1及第2阶段限值后的大型客车为对象,对车用燃油从原油开采、运输、炼油WTT(Well-to-Tank)到车辆使用TTW(Tank-to-Wheel)等多个环节,即燃料生命周期WTW(Well-to-Wheel)内的能量消耗和温室气体排放进行了定量分析,WTT阶段的分析使用了有关统计数据,TTW阶段的分析采用了试验数据.结果表明:WTW阶段的能量消耗和温室气体分别是TTW阶段的1.151倍和1.153倍;WTT阶段各环节的能量消耗占总能量消耗的比例分别为6.7%,0.42%,6.1%,温室气体排放占总排放的比例分别为1.92%,1.42%,9.97%;大型客车第1阶段燃料消耗量限值的实施可降低12%的能量消耗和11.8%的温室气体排放;第2阶段燃料消耗量限值的实施可降低16.93%的能量消耗和17.67%的温室气体排放.     

中心分级燃烧室预燃级贫油熄火性能试验

对一种单环腔的中心分级LESS（low emissions stirred swirl）燃烧室进行了常压状态下的贫油熄火性能试验研究.采用单头部试验件,研究了预燃级离心喷嘴流量数、进口温度及燃料类型对贫油熄火性能的影响.结果表明:预燃级采用小流量数的离心喷嘴能够降低贫油熄火当量比.进口温度低于150℃的范围内,随着进口温度的增加,贫油熄火当量比迅速降低;进口温度高于150℃时,温度对贫油熄火当量比的影响作用不明显.气态燃料与液态燃料的贫油熄火当量比随火焰筒压降的变化趋势是不同的,但都趋于相同的值,且在5%的火焰筒压降范围内,气态燃料的贫油熄火当量比低于液态燃料.      

Experimental study on NOx emission correlation of fuel staged combustion in a LPP combustor at high pressure based on NO-chemiluminescence

Experimental investigations on NO_x emissions of a single-cup, Lean Premixed Prevaporized (LPP), module combustor were carried out at elevated inlet temperature and pressure up to 810 K and 2.0 MPa, close to the real operating conditions of aero-engine combustors. This LPP combustor adopts centrally staged fuel injections which could produce separated stratified swirling spray flame. In the NO_x emissions measurements, the ranges of dome equivalence ratio and fuel stage ratio were from 0.55 to 0.58 and 8% to 24%, respectively. The optical diagnosis on separated stratified swirling spray flame were carried out with fuel stage ratio changing from 15% to 30%. Therefore, NO* and OH* chemiluminescence images were obtained. The results show that NO_x emissions increase with the increase of the fuel stage ratio. And from the chemiluminescence images, the main flame and pilot flame are found weakly coupled. The pilot flame plays a significant role in NO_x emission production because of its higher adiabatic flame temperature. Based on the results of chemiluminescence optical tests, a new NO_x emission prediction model is proposed based on the Lefebvre’s single flame model. The estimate of local equivalence ratio of the pilot stage’s non-premixed flame is modified considering the characteristics of spray combustion, and a “PLUS” emission prediction model suitable for separated stratified swirling spray flame is obtained. Compared to the experimental data, the “PLUS” model exhibits a good prediction in a range of ±13% of deviation.     

Simultaneous observations of some unusual whistlers and VLF hiss emission at a low L-value (L = 1.17)

The purpose of this paper is to describe some unusual whistlers (doublets and triplets) and VLF hiss emission recorded simultaneously on February 18, 1998 during nighttime at a low latitude Indian ground station Jammu (geomag. lat., 22° 26′ N; L = 1.17), and to make some discussions about their origin. The detailed structures of the observed VLF hiss emission clearly show that these emissions confined to a narrow continuous frequency band. Some times the frequency of hiss band oscillates and subsequently touches the upper edge of the first whistler component of the doublet. Detailed structures of the dynamic spectra of whistler and VLF hiss emission are briefly presented. From the dispersion analysis of the whistler doublets and triplets, it is found that the individual whistlers of the doublets and triplets simultaneously observed on the same day are one-hop whistlers having propagation path along higher and closely spaced L-values. Our result also shows that VLF hiss has been generated in the equatorial region of higher L-values. Generation and propagation mechanisms are briefly discussed.     

主燃孔位置对基于RQL高温升燃烧室流动与燃烧特性影响的数值模拟

为将富油燃烧/快速淬熄/贫油燃烧（RQL）用于高温升燃烧室设计，以实现温升与排放的良好统一，对不同主燃孔位置下 的单头部矩形燃烧室流动、淬熄区气流混合、燃烧和排放特性进行数值模拟。结果表明：燃烧室中心回流区的长度和高度随着主 燃孔轴向距离的增大而增大。随着主燃孔轴向距离的增大，主燃孔射流深度增加，射流角度逐渐向下游偏转，导致淬熄区内气流 的混合效果减弱；随着主燃孔位置的后移，富油区内的当量比显著增大，导致CO和碳烟的生成量迅速增加，淬熄区内的沿程高温 区域面积逐渐缩小，燃烧效率逐渐降低。当X/H=0.7时，燃烧室沿程NO生成量始终处在较大值；而当X/H=0.9时，燃烧室沿程NO 生成量始终处于较小值，但CO的生成量增大。