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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。
Wind tunnel test of open-air uniaxial tensioned aeroelastic model in uniform flow field was carried out to study the fluid-solid coupling mechanism of membrane structure. The results show that the instability of the aeroelastic membrane is mainly caused by the vortex induced vibration. The membrane structure deforms to the equilibrium position under the action of wind load and vibrates around the equilibrium position. Under certain wind speed, the fluid flows through the equilibrium position to generate vortex. In the low wind speed, the film vibrates mainly in the first-order mode, and there is no vortex in the flow field. When a certain wind speed is exceeded, a high-order mode response appears in the vibration, and the frequency of the membrane appears close to the dominant frequency With the increase of the wind speed, the difference between the dominant frequency of the vortex and the modal frequency of the vortex becomes smaller and smaller, and then changes to the same, and then changes to the greater and greater difference, resulting in the resonance response of the modal With the wind speed continues to increase, the frequency of the vortex will be close to the fundamental frequency of other modes of the membrane, resulting in vortex-induced resonance of the other modes of the structure. This kind of vortex-induced resonance is a periodic oscillatory instability. The structure has a dimensionless first critical wind velocity of about 0.84 and a second critical wind velocity of about 2.27.