非平稳脉动强风的模拟及开合结构减小结构风压的研究

Simulation of Unsteady Pulsating Strong Winds and Study of Open and Closed Structures to Reduce Structural Wind Pressure

强风会对大跨结构造成巨大的破坏,以往自然风对结构影响的研究中常将自然风速视为平稳的随机过程,但瞬时强风具有很强的非平稳特性。因此需要根据强风随时间变化的非平稳特性,即频率、平均值、谱函数对强风进行模拟合成,且结构抗风设计通常会采用增加结构强度或增大截面来防止瞬时强风造成的破坏,而使成本大大增加。采用对平均风下结构风压最大的区域设计开合结构,强风来袭时,通过控制结构开合来减小结构表面风压,防止风压过大产生结构损害。以河南某大跨发电站煤棚为例,采用谐波叠加法来模拟非平稳脉动风,并结合快速傅里叶变化算法加快运算,将模拟得到的非平稳脉动的强风作为入口的边界条件,通过ANSYS ICEM软件对普通结构和开合结构建模,并导入到ANSYS FLUENT软件中,采用大涡模拟法对普通结构和开合结构分别进行风洞模拟,对比相同非平稳脉动风下普通结构和开合结构的结构风压力,设计开合结构能够有效降低结构风压力满足抗风要求。

Strong winds can cause great damage to large-span structures,and previous studies of the effects of natural winds on structures often consider natural wind speed as a smooth random process,but transient strong winds have strong non-smooth characteristics,so it is necessary to simulate and synthesize strong winds according to the non-smooth characteristics of strong winds over time-frequency,average value,and spectral function,and the design of structural wind resistance usually adopts increasing structural strength or increase the cross-section to prevent the damage caused by a transient strong wind,which will make the cost greatly increased,using the design of open and closed structure for the area of the structure with the maximum wind pressure under the average wind,when the strong wind comes,through the control of the structure open and closed to reduce the surface wind pressure of the structure to prevent excessive wind pressure to produce structural damage.Taking a large-span power station coal shed in Henan Province as an example,the harmonic superposition method is used to simulate the non-smooth pulsating wind and combined with the fast Fourier variation algorithm to speed up the operation.The wind tunnel simulations are carried out separately for the common structure and the open-close structure in the simulation method,and the structural wind pressure of the common structure and the open-close structure under the same non-smooth pulsating wind is compared.