全文获取类型
收费全文 | 57篇 |
免费 | 53篇 |
国内免费 | 30篇 |
专业分类
航空 | 126篇 |
航天技术 | 6篇 |
综合类 | 4篇 |
航天 | 4篇 |
出版年
2023年 | 3篇 |
2022年 | 10篇 |
2021年 | 10篇 |
2020年 | 12篇 |
2019年 | 9篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2015年 | 6篇 |
2014年 | 1篇 |
2013年 | 10篇 |
2012年 | 8篇 |
2011年 | 2篇 |
2010年 | 2篇 |
2009年 | 5篇 |
2008年 | 2篇 |
2007年 | 4篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 1篇 |
2002年 | 2篇 |
2000年 | 6篇 |
1999年 | 9篇 |
1998年 | 7篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1989年 | 2篇 |
排序方式: 共有140条查询结果,搜索用时 15 毫秒
51.
弹性环挤压油膜阻尼器ERSFD是一种新型的旋转机械支点阻尼器,其良好的减振调频特性,能够有效地对转子振动进行控制。为了获得ERSFD-转子系统的临界转速特性,考虑了支点的刚度特性对临界转速的影响。首先,利用有限元接触分析技术和有限差分法计算,分别获得了弹性环和油膜的刚度特性,再通过ERSFD-转子系统的不平衡响应计算获得不同刚度特性下的临界转速特性,经转子动力特性试验验证,最终确定了影响临界转速的重要因素,即弹性环凸台处的接触状态。 相似文献
52.
53.
54.
55.
《中国航空学报》2023,36(1):290-310
Blade vibration monitoring can ensure the safe operation of aero-engine rotor blades. Among the methods of blade vibration monitoring, Blade Tip Timing (BTT) method has attracted more and more attention because of its advantages of non-contact measurement. However, it is difficult to install the Once-Per-Revolution (OPR) probe in the confined space of aero-engine, and the failure and instability of the OPR signal will reduce the reliability of the blade vibration analysis results, which directly affects the accuracy of the blade vibration parameters identification. The Multi-Probe linear fitting and Time of Arrival (ToA) Linear Correction method based on the BTT (MP-LC-BTT) without OPR is proposed to reduce the errors of single probe linear fitting method for blade vibration displacement analysis. The proposed method can also correct the calculation error of blade vibration displacement due to the nonlinear change of rotation speed, which can improve the analysis accuracy of the blade vibration displacement. A new blade vibration model conforming to the actual vibration characteristics is established, and the effectiveness of the proposed method is verified by numerical simulation. Finally, the reliability and accuracy of the MP-LC-BTT method have been verified by the experiments which include two high-speed blade test-benches and an industrial axial fan. This method can be used in the actual aero-engine monitoring instead of the BTT method with OPR. 相似文献
56.
针对传统BP算法存在的收敛速度慢以及容易陷入局部最小点等问题,给出了两种改进BP算法:LM(Levenberg-Marquardt)优化算法和SCG(Scaled Conjugate Gradient)算法,应用这两种算法对航空发动机转子故障进行诊断研究,比较它们之间的研究结果,仿真和实验表明LM优化算法比SCG算法具有更高的准确度和较快的收敛速度,可行性更强。 相似文献
57.
转子振动波德图的计算机辅助测试与分析系统 总被引:1,自引:0,他引:1
介绍了一种利用高性能数据采集卡及定时 /计数器卡对转子振动波德图进行测试与分析的系统。详细说明了系统的硬件结构及软件编制原理 ,并使用自行开发的Windows应用软件对一模拟转子系统进行了实验研究 相似文献
58.
The heat transfer in a novel smooth wedge-shaped cooling channel with lateral ejection of turbine blade trailing edge is experimentally investigated in both non-rotating and rotating cases. Beside the conventional inlet at the bottom of the channel, an extra coolant injection from 8 lateral non-equant holes is introduced to improve the overall heat transfer. The total mass flow rate ratio (lateral mass flow rate/total mass flow rate) varies from 0 to 1.0. The major inlet Reynolds number and rotation number respectively vary from 10000 to 20000 and from 0 to 1.16. Experimental results show that the lateral inlet decreases local bulk temperature and increases local heat transfer at the middle and the top of the static channel. In rotating cases, the lateral inlet notably improves the heat transfer at the high-radius half channel and compensates the negative effects induced by the rotation. Both intensity and uniformity of heat transfer inside the channel are enhanced while flow resistance decreases with proper mass flow rate ratio of coolant from two inlets. The most satisfactory total mass flow rate ratio is around 2/3. This new structural style of cooling channel has huge potential and provides new direction of heat transfer of turbine blade trailing edge. 相似文献
59.
Based on the acoustic mapping, a prediction model for the ground noise radiated from an in-flight helicopter is established. For the enhancement of calculation efficiency, a high-efficiency second-level acoustic radiation model capable of taking the influence of atmosphere absorption on noise into account is first developed by the combination of the point-source idea and the rotor noise radiation characteristics. The comparison between the present model and the direct computation method of noise is done and the high efficiency of the model is validated. Rotor free-wake analysis method and Ffowcs Williams-Hawkings (FW-H) equation are applied to the aerodynamics and noise prediction in the present model. Secondly, a database of noise spheres with the characteristic parameters of advance ratio and tip-path-plane angle is established by the helicopter trim model together with a parametric modeling approach. Furthermore, based on acoustic mapping, a method of rapid simulation for the ground noise radiated from an in-flight helicopter is developed. The noise footprint for AH-1 rotor is then calculated and the influence of some parameters including advance ratio and flight path angle on ground noise is deeply analyzed using the developed model. The results suggest that with the increase of advance ratio and flight path angle, the peak noise levels on the ground first increase and then decrease, in the meantime, the maximum Sound Exposure Level (SEL) noise on the ground shifts toward the advancing side of rotor. Besides, through the analysis of the effects of longitudinal forces on miss-distance and rotor Blade-Vortex Interaction (BVI) noise in descent flight, some meaningful results for reducing the BVI noise on the ground are obtained. 相似文献
60.
基于过程功率谱熵SVM的转子振动故障诊断方法 总被引:6,自引:4,他引:2
针对旋转机械振动过程的复杂性和振动故障产生的随机性以及振动故障样本获取难的问题,在信息熵理论的基础上,融合了支持向量机(SVM)小样本、全局性和泛化性好的优点,提出了过程功率谱信息熵(功率谱熵)SVM的故障诊断方法。结合转子实验台,得到了4种典型振动故障在多测点多转速下的数据,通过计算提取了其功率谱熵特征值作为故障样本,即故障向量,并建立SVM诊断模型,对转子振动故障的类别、严重程度和部位识别诊断,验证了该方法在转子振动故障诊断方面效果良好。 相似文献