摘要
The intrinsic interaction mechanism of flutter between the flow and structure of a rectangular plate remains a mystery from the viewpoint of unsteady flow.The present study provides a novel insight into this interaction mechanism based on an adequate understanding of the formation and evolution of the flapping leading-edge vortex(LEV).A series of wind tunnel tests was conducted to investigate the nonlinear flutter instability of an 8∶1 rectangular plate.The complete flow fields around the model throughout the flutter process were obtained by a particle image velocimetry(PIV)technique using two synchronous cameras with an interpolation and resampling method.To acquire the flow structures corresponding to the characteristic frequency of flutter,the spectral proper orthogonal decomposition(SPOD)method was extended to a noninertial frame to reconstruct the low-rank flow field during flutter and extract the characteristic flow pattern coupled with oscillations.It was found that when the 8∶1 rectangular plate undergoes flutter,the LEVs exhibit a periodic flapping phenomenon induced by the structure oscillations.A two-dimensional correlation analysis of the flapping LEVs was conducted for different inflow velocities.The results demonstrate that there is a substantial phase lead phenomenon in the LEV evolution downstream for a higher inflow velocity.This phenomenon may be related to a phase offset of aerodynamic forces,and finally,it gives rise to flutter.
当前钝体平板颤振研究中,非定常流动与结构振动之间的相互作用机制尚未明晰。本文探究了8∶1矩形平板颤振过程中前缘涡的形成与演化机制,为揭示颤振的流固耦合机理提供了新的视角。开展了一系列风洞试验,对8∶1矩形平板的非线性颤振失稳特性进行了研究。采用粒子图像测速技术(PIV)和流场插值重构方法,获取了8∶1矩形平板发生颤振前后完整的绕流场特征。为了进一步分析与颤振耦合频率相关的特征流态,将谱本征正交分解方法(SPOD)拓展至非惯性参考系,实现了非稳态振动边界下颤振绕流场重构和颤振相关特征流动结构提取,发现8∶1矩形平板发生颤振时,前缘涡受结构振动诱导出现周期性拍动现象。对不同来流速度下拍动前缘涡结构进行相关性分析,结果表明,前缘涡演化随风速提高呈现出显著的相位前移现象,进而诱发气动力同样发生相位前移,最终导致颤振发生。
作者
LI Wenjie
LAIMA Shujin
李文杰;赖马树金(哈尔滨工业大学教育部结构动力行为与控制重点实验室,哈尔滨150090;哈尔滨工业大学土木工程智能防灾减灾工信部重点实验室,哈尔滨150090;哈尔滨工业大学土木工程学院,哈尔滨150090)
基金
The National Natural Science Foundation of China(No.52178470)
the National Key Research and Development Program of China(No.2022YFC3005303).
