排序方式: 共有107条查询结果,搜索用时 60 毫秒
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为了研究中心分级贫油低排放燃烧室的排放特性和排放预测方法,针对一个低排放头部方案,在单头部燃烧室试验件上,在不同的温度、压力、油气比、供油模式和分级比条件下,测量其排放性能。以Lefebvre排放经验预测公式为基础,采用经验分析方法拟合排放试验数据,归纳出适用于本头部方案的排放预测公式。表征预测好坏的判定系数R2在小工况下和大工况下分别为0.95和0.93,表明预测结果与试验结果符合度较好。小工况和大工况排放特性不同,对仅预燃级喷油的小工况工作模式,NO_x排放主要受化学恰当燃烧温度和预燃级局部当量比的影响;对预燃级和主燃级同时喷油的大工况工作模式,NO_x排放主要受燃烧区温度和主燃级燃油比例的影响。 相似文献
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This study explores the design, analysis, and air pressure drop assessment of three analogous air–fuel heat exchangers consisting of thin serpentine tube bundles intended for use in high Mach number aero-engines. In high speed flight, the compressor bleed air used to cool high temperature turbine blades and other hot components is too hot. Hence, aviation kerosene is applied to precool the compressor bleed air by means of novel air–fuel heat exchangers. Three light and compact heat exchangers in... 相似文献
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陈淑仙 《中国民航飞行学院学报》2011,22(2):33-35
结合机务专业"航空发动机构造"课的教学实践,阐述了针对课程特点激发学生学习兴趣、丰富教学手段、优化教学方法、改革作业形式、开展现场教学的重要性及其具体实施办法.首次应用三维虚拟发动机辅助教学、并引入机务维修工作中发动机结构图作为课程作业用图.本研究成果为提高"航空发动机构造"课的教学效果探索出了一套行之有效的方法. 相似文献
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等离子体助燃是一种新型的强化燃烧技术,近年来受到国内外学者的广泛关注。本文开创性地研制了基于旋转滑动弧等离子体的强化燃烧头部,建立了某型航空发动机三头部燃烧室实验件的等离子体助燃实验平台,验证了该等离子体强化燃烧技术应用于型号发动机燃烧室的可行性。实验研究等离子体助燃在不同余气系数和不同输入电压条件下对平均出口温度、燃烧效率、温度分布系数以及熄火边界的影响。实验结果表明,与正常燃烧相比,施加等离子体助燃后的燃烧效率有明显的提高,在输入电压为U0=240V,余气系数为 α=0.8时,等离子体助燃的燃烧效率提高3.24%。实施等离子体助燃后,燃烧室出口温度分布场分布得到明显的改善,在富油工况α=0.8,出口温度分布系数减少39.8%。等离子体助燃输入电压越高熄火边界扩展程度越明显,相比于正常工况条件下,等离子体助燃U0=240V的熄火边界扩宽了7.34%。 相似文献
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Rotating experimental investigations were carried out to study the oil sealing capability of two different floating ring seals in cold/hot state for aero-engine. High-speed Floating Ring Seal(HFRS) is a seal with the inner diameter of 83.72 mm and maximum speed of 38000 r/min, and Low-speed Floating Ring Seal(LFRS) is another seal with the inner diameter of 40.01 mm and maximum speed of 18000 r/min. In hot state, sealing air with the temperature of 371 K and oil with the temperature of 343 K was employed to model the working conditions of an aero-engine. Comparisons between floating ring seal and labyrinth seal were done to inspect the leakage performance.More attention was paid to the critical pressure ratio where the oil leakage began. Results show that the critical pressure ratio in cold state is obviously larger than that in hot state for both seals. An underlying sealing mechanism for floating ring seal is clarified by the fluid film, which closely associates with the dimensionless parameter of clearance over rotating diameter(2 c/Dr). Another fantastic phenomenon is that the leakage coefficient in hot state, not the leakage magnitude, is unexpectedly larger than that in cold state. Overall, the leakage performance of the floating ring seal is better than the labyrinth seal. 相似文献
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《中国航空学报》2021,34(2):343-357
Tip clearances of multistage rotors and stators greatly affect aero-engines’ aerodynamic efficiency, stability and safety. The inevitable machining and assembly errors, as well as the complicated error propagation mechanism, cause overproof or non-uniform tip clearances. However, it is generally accepted that tip clearances are difficult to predict, even under assembly state. In this paper, a tip clearance prediction model is proposed based on measured error data. Some 3D error propagation sub-models, regarding rotors, supports and casings, are built and combined. The complex error coupling relationship is uncovered using mathematical methods. Rotor and stator tip clearances are predicted and analyzed in different phase angles. The maximum, minimum and average tip clearances can be calculated. The proposed model is implemented by a computer program, and a case study illustrates its performance and verifies its feasibility. The results can be referred by engineers in assembly quality judgement and decision-making. 相似文献
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涡轮叶片前缘双排孔气膜冷却数值模拟 总被引:3,自引:2,他引:1
为了解冷气喷射对涡轮叶片前缘气膜冷却特性的影响,对圆柱形前缘双排孔气膜冷却进行全三维N-S方程数值模拟。计算域网格采用FNM形式的多块结构化网格。研究了射流与主流的流动机理,分析了不同吹风比下对壁面冷却效率的影响。计算结果表明,壁面平均绝热效率随吹风比的增大而升高。针对第二排孔结构参数进行优化设计,优化后的冷却效果要明显优于原始结构。 相似文献
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《中国航空学报》2019,32(8):2009-2016
The Blade Integrated Disk (Blisk) is one of the key components in the aero-engine, it is generally manufactured by the multi-axis milling and almost 90% raw materials are removed. To avoid the full immersion of a cutter in the rough machining of a blisk channel, the trochoidal milling is a promising strategy since it can keep a small immersion angle in the rough milling process while maintaining the high machining efficiency. However, while toolpaths are being planned for the trochoidal milling process, the conventional methods are mainly for the planar machining area with fixed tool orientations, which cannot be used for complex channels where the multi-axis machining should be employed. To this end, this paper presents a four-axis trochoidal toolpath planning method with a ball-end cutter, and thus the blisk channel can be machined efficiently. For this to happen, the trochoidal paths are planned in the parametric domain and then mapped into the physical domain, with tool orientations controlled by the quaternion interpolation method to have smooth tool movement along the toolpaths. Both geometric simulation and physical milling experiments of the proposed method have convincingly demonstrated the validation of the proposed method. 相似文献
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