8∶1矩形平板颤振流固耦合机理试验研究OA

The intrinsic interaction mechanism of flutter be-tween 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 mecha-nism 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 velocim-etry(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 re-construct 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 in-duced by the structure oscillations.A two-dimensional cor-relation analysis of the flapping LEVs was conducted for dif-ferent inflow velocities.The results demonstrate that there is a substantial phase lead phenomenon in the LEV evolu-tion downstream for a higher inflow velocity.This phenom-enon may be related to a phase offset of aerodynamic forces,and finally,it gives rise to flutter.