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Effects of tip perturbation and wing locations on rolling oscillation induced by forebody vortices 总被引:1,自引:0,他引:1
The wing rock motion is frequently suffered by a wing-body configuration with low swept wing at high angle of attack. It is found from our experimental study that the tip perturbation and wing longitudinal locations affect significantly the wing rock motion of a wing-body. The natural tip perturbation would make the wing rock motion of a nondeterministic nature and an artificial mini-tip perturbation would make the wing rock motion deterministic. The artificial tip perturbation would, as its circumferential location is varied, generate three different types of motion patterns: (1) limit cycle oscillation, (2) irregular oscillation, (3) equilibrium state with tiny oscillation. The amplitude of rolling oscillation corresponding to the limit cycle oscillatory motion pattern is decreased with the wing location shifting downstream along the body axis. 相似文献
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通过理论研究以及高频仿真相结合的方法分析设计了一款新型Ka波段8路径向波导空间功率分配(合成)器。研发的新结构输入输出段为标准矩形波导结构,代替了传统功率分配(合成)器输入输出段的同轴结构,这种新型全金属结构更加简单紧凑,更易于加工。仿真结果表明:功率分配(合成)器工作带宽达到了34%(12GHz),基本覆盖整个Ka波段;全频带内反射系数S11低于-20dB,各支路的相位差均小于5°。通过在同轴波导渐变段引入切比雪夫渐变结构,在减小了器件尺寸的同时,在整个频带内的网络S参数也不错。这款新型Ka波段8路径向波导功率分配(合成)器将应用于前级固态功率放大器,推动回旋行波管项目研发。 相似文献
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用中子激活方法,对气态P2O5在SiO2-Si系统中的扩散分布进行了直接测量。样品为p型Si单晶,电阻率为3—5欧姆·厘米,氧化层是在1250℃下水汽中生长的,其厚度为0.45—0.47微米。实验结果表明:对于完全掩蔽的样品,磷在SiO2层中的浓度分布有个陡峭的边界;对于掩蔽失效情形,在靠近SiO2-Si交界面约0.1微米的SiO2层内,磷的浓度显著地降低,出现一个明显的交界层,在交界层以外的SiO2层中磷的浓度是均匀的和恒定的,而交界层中磷的浓度及磷在Si中的表面浓度都随时间的延长而显著地升高,文中对所得的结果作了简单讨论。 相似文献
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用示踪原子方法,研究了磷(Na2HP32O4)在p型硅表面氧化层中的扩散。硅单晶的电阻率为5—6欧姆·厘米。氧化层是在高温下水汽中生长的,其厚度为0.5—0.6微米,是用灵敏度为10-5克/刻度的微量天平测定的。发现在1245℃时氧化层的生长规律服从X1.85=1.4×10-2t,其中X为氧化层的厚度,单位为微米;t为氧化层的生长时间,单位为分钟。其红外吸收的测量结果与文献中的数据基本一致。扩散是在充满空气的封闭石英管中进行的,扩散温度为700—1250℃,扩散时间从4分钟到5小时。实验结果表明,磷在SiO2层中的浓度分布不能直接用菲克第二定律描述,它可以看成是一个均匀分布和一个遵守菲克第二定律的分布的迭加。按后一种分布得到在700—1200℃范围内的扩散系数的温度依赖关系:D=1.9×10-9exp(-1.1/kT)厘米2/秒。均匀分布部分的浓度为(1—8)×1019原子/厘米3。大中对所用方法和所得结果作了简单讨论. 相似文献
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利用壁面压力测量和表面油流显示技术对后掠压缩角产生的激波与湍流边界层干扰进行了实验研究。主要研究了来流马赫数对干扰分离特性和起始分离条件的影响,实验的马赫数为1.79,2.04和2.50,相应的雷诺数为2.42—2.47×10 ̄7/m.实验模型共15个,其后掠角变化范围是0°—60°,流向压缩角变化范围是10°—30°,实验结果表明,与二维干扰不同,对于大后掠角的三维干扰来说,分离线上的压比和起始分离时的无粘激波压比近似相等,且是一个与马赫数无关的常数。 相似文献
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Asymmetric vortices flow over slender body and its active control at high angle of attack 总被引:5,自引:0,他引:5
The studies of asymmetric vortices flow over slender body and its active control at high angles of attack have significant
importance for both academic field and engineering area. This paper attempts to provide an update state of art to the investigations
on the fields of forebody asymmetric vortices. This review emphasizes the correlation between micro-perturbation on the model
nose and its response and evolution behaviors of the asymmetric vortices. The critical issues are discussed, which include
the formation and evolution mechanism of asymmetric multi-vortices; main behaviors of asymmetric vortices flow including its
deterministic feature and vortices flow structure; the evolution and development of asymmetric vortices under the perturbation
on the model nose; forebody vortex active control especially discussed micro-perturbation active control concept and technique
in more detail. However present understanding in this area is still very limited and this paper tries to identify the key
unknown problems in the concluding remarks.
The project supported by the National Natural Science Foundation of China (10172017), Aeronautical Science Foundation of China
(02A51048) and Foundation of National Key Laboratory of Aerodynamic Design and Research (51462020504HK0101) 相似文献
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A CRITICAL PATTERN OF CROSSFLOW AROUND A SLENDER 总被引:1,自引:0,他引:1
IntroductionModernhigh_performancefightersoftenrequiretobeoperatedunderafairlylargeangleofattacksoastoachieveexcellentmaneuverabilityandagility .Atsuchlargeangleofattack ,asymmetricallee_sidevortexflowwillformatthefrontpartofthefuselage .Sothatsuchagreats… 相似文献