单向张拉膜结构气弹模型试验研究

在均匀流场中进行开敞式单向张拉膜结构气弹模型风洞试验，研究膜结构的流固耦合机理。研究表明：膜的气弹失稳主要由涡激共振引起，膜结构在风荷载作用下变形到平衡位置并围绕该平衡位置进行振动，特定风速下，流体流经平衡位置会产生旋涡。低风速下，膜以一阶模态为主振动，流场中没有任何旋涡；超过一定风速后，振动中出现了某高阶模态的响应，流场中也出现了与该阶模态主频接近的旋涡；随着风速的增大，旋涡的主频与该阶模态频率的差别越来越小进而变化到相等，后又变化到差别越来越大，导致该阶模态的共振响应越来越弱直至消失；随着风速的继续增大，旋涡的频率会与膜的其他阶模态基频接近，导致结构发生其他阶模态的涡激共振。这种涡激共振是一种周期性振荡式失稳，结构的无量纲第一临界风速约为0.84，第二临界风速约为2.27。

Aeroelastic experiment of one-way tensioned membrane structure

An open-type one-way tensioned membrane was tested in uniform flow to discuss the fluid-structure interaction mechanism of the membrane structure. It is shown that the aeroelastic instability of the structure is caused by the vortex-induced resonance. The membrane was deformed to an equilibrium position then vibrated around this position up and down. At lower wind speeds, the membrane structure vibrated in the first order mode and there was no vortex above the membrane; at certain wind speed, a higher order mode occurred in the resonant responses and there came to a vortex whose frequency was close to that of the higher order mode. With the increasing of the wind speed, the difference of the frequencies between the vortex and the vibrating mode changed from smaller and smaller to bigger and bigger. Later, the frequency of the vortex became to be close to the frequency of another vibrating mode and caused another resonance. This study also shows that this kind of resonance is a periodical oscillatory instability and the 1st nondimensional critical wind velocity is about 0.84 and the 2nd critical wind velocity is about 2.27.