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雷诺数对于方柱流致振动能量收集系统的影响 被引量:4
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作者 韩鹏 潘光 +1 位作者 黄桥高 施瑶 《西北工业大学学报》 EI CAS CSCD 北大核心 2020年第5期928-936,共9页
在来流作用下,相较于圆柱,方形柱体会发生更为明显的振动响应,其具备良好的海洋能量收集特性。针对方柱流致振动能量收集系统展开数值模拟研究,结合SST k⁃ω湍流模型求解URANS方程来获得流场信息,并通过Newmark⁃β方法求解固体振动方程... 在来流作用下,相较于圆柱,方形柱体会发生更为明显的振动响应,其具备良好的海洋能量收集特性。针对方柱流致振动能量收集系统展开数值模拟研究,结合SST k⁃ω湍流模型求解URANS方程来获得流场信息,并通过Newmark⁃β方法求解固体振动方程。计算方法与实验数据及其他仿真模拟结果进行了对比,取得了良好的一致性。文章所选取的雷诺数范围为24000~160000,相应折合速度为3<Ur<20。结果表明,雷诺数对方柱的频率响应、振幅响应、脱涡模式以及能量获取效率均有不可忽视的影响。当雷诺数为88000时整个系统能量收集效率最高,为7.156%;在雷诺数大于120000后,方柱由涡激振动转向驰振,其振动响应及能量收集特性发生大幅变化,在雷诺数超过144000后方柱进入完全驰振状态。 展开更多
关键词 涡激振动 驰振 海流能能量捕获 雷诺数 方柱
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Nondestructive and Fast Vibration Phenotyping of Plants 被引量:1
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作者 E.de Langre O.Penalver +5 位作者 P.Hémon J.-M.Frachisse M.-B.Bogeat-Triboulot B.Niez E.Badel B.Moulia 《Plant Phenomics》 2019年第1期152-161,共10页
The frequencies of free oscillations of plants,or plant parts,depend on their geometries,stiffnesses,and masses.Besides direct biomechanical interest,free frequencies also provide insights into plant properties that c... The frequencies of free oscillations of plants,or plant parts,depend on their geometries,stiffnesses,and masses.Besides direct biomechanical interest,free frequencies also provide insights into plant properties that can usually only bemeasured destructively or with low-throughput techniques(e.g.,change inmass,tissue density,or stiffness over development or with stresses).We propose here a new high-throughput method based on the noncontact measurements of the free frequencies of the standing plant.The plant is excited by short air pulses(typically 100ms).The resulting motion is recorded by a high speed video camera(100 fps)and processed using fast space and time correlation algorithms.In less than aminute the mechanical behavior of the plant is tested over several directions.The performance and versatility of this method has been tested in three contrasted species:tobacco(Nicotiana benthamian),wheat(Triticum aestivum L.),and poplar(Populus sp.),for a total ofmore than 4000 data points.In tobaccowe show that water stress decreased the free frequency by 15%.In wheat we could detect variations of less than 1 g in the mass of spikes.In poplar we could measure frequencies of both the whole stem and leaves.The work provides insight into new potential directions for development of phenotyping. 展开更多
关键词 DIRECTIONS VIBRATION INSIGHT
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