封闭式单向张拉膜结构气弹失稳机理研究

发布时间：2018-08-25 19:33

【摘要】：在均匀流场中进行了封闭式单向张拉膜结构气弹模型风洞试验,考察了膜预张力和来流风速对结构振幅、振动模态和总阻尼比的影响,以及膜面位移与膜上方流场的频谱相关性,分析了封闭式膜结构的气弹失稳机理,给出了气弹失稳无量纲临界风速。研究结果表明:低风速下(无量纲风速小于1.2时),流场中的旋涡主频远低于结构基频,结构以受迫振动为主;随着风速增大,流场中出现与结构2阶反对称模态频率接近的旋涡,导致结构发生以2阶模态大幅振动为特征的涡激共振,且在无量纲风速不小于1.2的风速范围内出现振动锁定现象,结构总阻尼比迅速衰减接近0。由此可认为,封闭式膜结构的气弹失稳由涡激共振引起,结构振幅的突然增大、主导振动模态的突然改变以及总阻尼比的突然减小为其主要特征;气弹失稳无量纲临界风速约为1.2。
[Abstract]:Aeroelastic model wind tunnel tests of a closed unidirectional tensioned membrane structure are carried out in a uniform flow field. The effects of membrane pretension and flow velocity on the amplitude, vibration mode and total damping ratio of the structure are investigated. The correlation between the displacement of the membrane surface and the frequency spectrum of the flow field over the membrane is discussed. The mechanism of the aero-elastic instability of the closed membrane structure is analyzed and the dimensionless critical wind speed of the aero-elastic instability is given. The results show that at low wind speed (dimensionless wind speed < 1.2), the main frequency of vortex in the flow field is far lower than the fundamental frequency of the structure, and the structure is dominated by forced vibration, and with the increase of wind speed, The vortex in the flow field is close to the second order antisymmetric mode frequency of the structure, which leads to the vortex-induced resonance, which is characterized by the large vibration of the second order mode, and the vibration locking phenomenon occurs in the range of dimensionless wind speed of not less than 1.2. The total damping ratio of the structure decays rapidly close to 0. It can be concluded that the aero-elastic instability of the closed membrane structure is caused by vortex-induced resonance, the sudden increase of the amplitude of the structure, the sudden change of the dominant vibration mode and the sudden decrease of the total damping ratio are the main characteristics of the aero-elastic instability of the closed membrane structure. The dimensionless critical wind speed of Aeroelastic instability is about 1.2.
【作者单位】：哈尔滨工业大学结构工程灾变与控制教育部重点实验室;哈尔滨工业大学土木工程学院;
【基金】：国家自然科学基金重大研究计划重点项目(91215302);国家自然科学基金项目(50908068)
【分类号】：TU38

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