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A rigid mode of long-span cantilevered roof was tested in wind tunnel.By analyzing the relation between wind angle and wind pressure coefficient and the relation between wind angle and wind shape factor,we found that 90° is the most disadvantageous wind angle.Furthermore,the fluctuation of wind pressure at the windward edge was reflected by power spectrum density (PSD) and coherence function.The correlation coefficients of measuring points on outer and inner surfaces verifys that the largest lift force was produced at 90°. 相似文献
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The present paper investigates the feasibility of modal expansion-based virtual sensing in the context of offshore wind jacket substructures. For this specific application, issues have been reported when expanding wind-driven brace vibrations and wave-driven vibrations in the splash-zone based on a sensor network placed solely above the sea level. These limitations are addressed in this paper by extending the sensor network with sub-sea vibration sensors and a wave radar sensor, which allow for capturing local brace vibration modes and the wave-driven vibration response. The brace expansion is thus improved by including the local brace vibration modes in the expansion basis, while the representation of wave-driven vibrations is improved by including load-dependent Ritz vectors computed based on input from the wave radar sensor. The merit of the proposed extension is explored using a numerical model of an offshore wind turbine supported by a jacket substructure in a simulation setting with different operational and environmental conditions. It is documented that the extended setup provides an improvement in the expansion-based estimation of both wind- and wave-driven vibrations. The former improvement is particularly relevant for operational cases, while the latter is relevant for idling cases. Despite the documented improvements, a systematic reduction in the expansion quality is observed for higher wind speeds in operational cases for both the basic and the extended setup. It is contended that this phenomenon is due to the operational variability of the controller, which violates the fundamental assumption of the structural system being linear and time-invariant. 相似文献
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文章论述了扩容改建后的现柴油机中冷气试验台风洞电加热段的空气压力损失和空气流量测量段的流场情况。给出了柴油机中冷器空气压力损失系统及其相应的实际空气压力损失的计算方法。 相似文献
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电气化铁路接触网风致舞动研究现状与进展 总被引:2,自引:2,他引:0
《铁道标准设计通讯》2015,(9):145-148
为了应对电气化铁路接触网风致舞动灾害对我国铁路交通运输造成的不利影响,总结一系列国内外接触网舞动相关的文献。舞动现象内在原因复杂,当前舞动机理性研究中的邓哈托判定以及尼格尔判定都对实际情况作出较大简化,现有的舞动理论并不能准确的定量分析接触网舞动现象;通过研发防舞装置来抑制接触网舞动发生是一种可行的方法;有限元模拟分析可以为研究舞动开辟新的思路。最后对接触网舞动研究中的有待解决的问题进行归纳,并提出需进一步研究的内容和方法。 相似文献