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551.
552.
随着飞机适航要求的提高,进口畸变对燃气轮机的影响也逐渐被重视起来。而飞行过程中燃气轮机所遇到的进口畸变经过动叶的传递后,往往会严重影响静叶进口气流角分布的均匀性,并恶化静叶的通流能力。为研究气流角畸变对静叶流场的影响,针对带有可调导叶的扇形叶栅,通过单独调整一片导叶角度而其它导叶角度不变的方式制造静叶进口畸变流场,并开展实验与仿真研究,分析该方法制造的畸变流场结构及其对静叶气动特性的影响。研究表明,采用的8号导叶旋转6°而其它导叶角度不变的方法可以改变静叶进口气流角、轴向速度、静压等参数的周向均匀度,实现静叶进口畸变流场。与均匀进口相比,气流角畸变度为3.22,气流角畸变度增加了1.14,并增加了静叶S8吸力面根部下通道涡的损失与影响范围,而对叶顶与中径处的影响相对较小。此外,受畸变流场影响的静叶流道总压恢复系数较均匀条件下略有下降。 相似文献
553.
In this study,firstly,for the axisymmetric RVABI,the change-rule of adverse pressure gradient caused by radial velocity during the transition of internal flow mode in variable geometry is summarized,and a Bypass Ratio(BR) iterative algorithm based on the empirical correlation of non-equilibrium pressure is proposed.The algorithm can estimate the nonlinear relationship between area ratio and BR,with an error range falling below 6.5%.Then,we discuss the favorable effect of uniform mixing on the th... 相似文献
554.
《中国航空学报》2023,36(2):127-138
Before the dispatch of the carrier-based aircraft, a series of pre-flight preparation operations need to be completed on the flight deck. Flight deck fixed aviation support resource station configuration has an important impact on operation efficiency and sortie rate. However, the resource station configuration is determined during the aircraft carrier design phase and is rarely modified as required, which may not be suitable for some pre-flight preparation missions. In order to solve the above defects, the joint optimization of flight deck resource station configuration and aircraft carrier pre-flight preparation scheduling is studied in this paper, which is formulated as a two-tier optimization decision-making framework. An improved variable neighborhood search algorithm with four original neighborhood structures is presented. Dispatch mission experiment and algorithm performance comparison experiment are carried out in the computational experiment section. The correlation between the pre-flight preparation time (makespan) and flight deck cabin occupancy percentage is given, and advantages of the proposed algorithm in solving the mathematical model are verified. 相似文献
555.
《中国航空学报》2023,36(2):139-148
This paper focuses on fixed-interval smoothing for stochastic hybrid systems. When the truth-mode mismatch is encountered, existing smoothing methods based on fixed structure of model-set have significant performance degradation and are inapplicable. We develop a fixed-interval smoothing method based on forward- and backward-filtering in the Variable Structure Multiple Model (VSMM) framework in this paper. We propose to use the Simplified Equivalent model Interacting Multiple Model (SEIMM) in the forward and the backward filters to handle the difficulty of different mode-sets used in both filters, and design a re-filtering procedure in the model-switching stage to enhance the estimation performance. To improve the computational efficiency, we make the basic model-set adaptive by the Likely-Model Set (LMS) algorithm. It turns out that the smoothing performance is further improved by the LMS due to less competition among models. Simulation results are provided to demonstrate the better performance and the computational efficiency of our proposed smoothing algorithms. 相似文献
556.
建立了变循环发动机整机模型并对可变几何低压涡轮特性进行修正,研究了低压涡轮导叶开度从-6°~6°时对各部件以及发动机整体性能的影响。结果表明:随低压涡轮导向器角度变大,低压涡轮进口折合流量增大,不论低压涡轮导向器开大或关小,高、低涡轮效率均下降;随导叶开度增大,高压涡轮膨胀比增大,高压轴功率增大,高压压气机(High pressure compressor,HPC)与核心机驱动风扇级(Core driven fan stage,CDFS)压比增大;双外涵模式下涡轮导叶角度为0°时单位推力最大,单外涵模式下涡轮角度为-1°时单位推力最大。 相似文献
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2219 铝合金气孔敏感性较强,变极性TIG 焊接工艺可以有效减少和抑制气孔产生,是适合于
2219 铝合金的焊接工艺。本文介绍了2219T62 铝合金VPTIG 焊接接头的拉伸性能,进行了拉伸断口形貌分析
和微观组织分析。结果表明:2219T62 铝合金VPTIG 焊接接头强度系数可以达到65% 以上,焊接接头为混合
断裂方式,VPTIG 焊缝盖面层气孔相比打底层较多。 相似文献
2219 铝合金的焊接工艺。本文介绍了2219T62 铝合金VPTIG 焊接接头的拉伸性能,进行了拉伸断口形貌分析
和微观组织分析。结果表明:2219T62 铝合金VPTIG 焊接接头强度系数可以达到65% 以上,焊接接头为混合
断裂方式,VPTIG 焊缝盖面层气孔相比打底层较多。 相似文献