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121.
金刚石锯片切割性的评价方法和检测系统的研制 总被引:1,自引:0,他引:1
本文探讨了金刚石锯片切割性能的评价方法,基于此方法,应用多参数检测技术和LabVIEW软件平台开发出一套金刚石锯片性能检测系统。该系统可以实时的实现金刚石锯片切割性能参数的采集、显示、分析、存储和回放等功能。通过保存的数据可以方便的求出试验锯片的最大给进速度和平均给进速度以及功率的最大值和平均值等,来综合评价锯片的切割性能。 相似文献
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Radar‐based structural health monitoring of wind turbine blades: The case of damage localization 下载免费PDF全文
Philip Arnold Jochen Moll Moritz Mälzer Viktor Krozer Dimitry Pozdniakov Rahmi Salman Stephan Rediske Markus Scholz Herbert Friedmann Andreas Nuber 《风能》2018,21(8):676-680
This short communication reports on a radar approach for structural health monitoring of wind turbine blades. Therefore, a bistatic frequency‐modulated continuous wave (FMCW) radar in the frequency range from 33.4 to 36.0 GHz has been developed and tested experimentally using a laboratory wind turbine demonstrator. A differential damage localization framework is presented here that exploits signal differences between measurements from the intact and the damaged structure for 3D imaging of the defect. We have achieved the localization of a 30‐mm cut in a glass fiber composite structure as well as the localization of a water pack at the backside of the specimen with a localization error of several centimeters. 相似文献
124.
通过阐述轴流风机失速和喘振的机理,分析实际生产中轴流风机失速和喘振的发生原因,并对600MW机组双级轴流一次风机运行中叶片漂移的原因进行讨论,提出在检修工作中应注意的问题及其解决措施。 相似文献
125.
针对45°叶型转折角扩压叶栅及增加小叶片后组成的大小叶片叶栅,分别测量了其在设计工况及不同气流攻角下的叶栅气动性能,通过PIV实验获得了对应工况下的叶栅内部流动状态.结果表明:增加小叶片后,叶片压力面至吸力面的压力梯度明显降低,大叶片载荷降低;在设计工况下,叶栅气流落后角仍可参考霍威尔半经验公式进行计算,但偏离设计工况后,该公式存在较大误差;大小叶片叶栅的气流落后角仅在小气流攻角下明显减小,在其余工况下变化不大;不同气流攻角下小叶片对大叶片表面气流流动分离起到约束作用;在设计工况至大气流攻角工况变化过程中,叶栅扩压损失有所降低. 相似文献
126.
《Journal of Nuclear Science and Technology》2013,50(11):1298-1310
From the neutronic viewpoint, the optimization of BWR core designs is strongly related to the accurate determination of flux variations inside and around fuel assemblies. These fluctuations, which are mainly due to the high heterogeneity of the fuel and moderator regions, as additionally to the presence of cruciform absorber blades, have a direct impact on reactor safety and performance. Of particular importance is the pin power distribution, leading to the need of assessing the capabilities of design tools in a sufficiently rigorous manner. The basic configuration chosen for the code comparisons corresponds to a SVEA-96 fuel assembly under full-density water moderation conditions, with inserted hafnium absorber blades. The calculational schemes employed are the Monte Carlo code MCNPX2.5, in conjunction with various nuclear data libraries (ENDF/B-VI, JEF2.2, JEFF3.0, JENDL-3.2 and JENDL3.3), and the deterministic codes CASMO4 with JEF2.2, BOXER with JEF1.0 and HELIOS 1.6 with ENDF/B-VI based libraries, respectively. The significant discrepancies observed in k ∞ predictions (>500pcm) are found to be mainly nuclear data related. On the other hand, data library effects have been found to be quite small for the prediction of pin-wise distributions of total fissions (Ftot), 238U captures (C8), as also of the C8=Ftot ratio. Significant differences in these reaction rate distributions (up to several percent) have, however, been observed between the Monte Carlo and deterministic calculations, particularly in the vicinity of the hafnium blades and in the gadolinium pins. 相似文献
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128.
Florian Sayer Falko Bürkner Benjamin Buchholz Michael Strobel Arno M. van Wingerde Hans‐Gerd Busmann Henry Seifert 《风能》2013,16(2):163-174
This paper presents results out of investigations of the DEBRA‐25 wind turbine blades. Almost unique in the history of modern wind energy, these blades were in operation for 18 years next to a weather station and were investigated afterward. Therefore, the loads experienced in the operational life could be post‐processed accurately with the measured data of the weather station and the turbine. The blades are made of materials that are similar with today's wind turbines. Furthermore, intensive laboratory tests and free field tests have been carried out, and all load assumptions and data and results are still available today. The results include experimental investigations on the moisture content of the load‐carrying material, static and fatigue behavior of the material, the relaxation of the coupling joints, the natural frequencies of the blade and a full scale static blade test. It is shown that the structural performance of the DEBRA‐25 service blades is comparable with modern wind turbine blades. Although some damage was found by visual inspection, the service blade of the DEBRA‐25 showed excellent mechanical behavior in the full scale blade test. Only small changes of the edgewise eigenfrequencies were detected. The pre‐tensioning forces of the IKEA bolts, where the two blade parts are connected, were measured and were still adequate. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
129.
Blade number effect for a ducted wind turbine 总被引:1,自引:0,他引:1
Sheng-Huan Wang Shih-Hsiung Chen 《Journal of Mechanical Science and Technology》2008,22(10):1984-1992
Ducted wind turbine with multiple blades installed was believed to have a good wind power energy conversion effect. However,
little information was available on how to design a good ducted wind turbine. In this paper the effects of blade number on
a ducted wind turbine performance is studied. Numerical studies using CFD method to simulate the wind turbine performance
were adopted. The duct is a converging-diverging nozzle with the turbine blades located at the throat. A rated output of a
1-kW turbine is adopted as the baseline design. It was found that the blade geometry, stagger angle, and number of blades
have different duct blockage effects, and do affect the turbine performance (specifically the power coefficient and torque
coefficient, etc.). The fewer number of blades has higher through flow speed, while the larger number of blades provides larger
torque. The best power coefficient lies in between the two extremes. The appropriate number of blades is important to match
the generator performance curve for optimal overall performance and efficiency.
This paper was presented at the 9th Asian International Conference on Fluid Machinery (AICFM9), Jeju Korea, October 16–19, 2007. 相似文献
130.