Improvements in low dimensional tools for flow-structure interaction problems: Using global POD

In this paper improvements in the low dimensional tool for flow-structure interaction problems based on Proper Orgthgonal Decomposition (POD) and modified Linear Stoachastic Estimation (mLSE) are shown and were applied to a Micro Air Vehicle (MAV) wing. The method utilizes the dynamic strain measurements from the wing to estimate the POD expansion coefficients from which an estimation of the velocity in the wake can be obtained. For this experiment the MAV wing was set at five different angles of attack, from 0° to 20°. The tunnel velocities varied from 44 to 58ft/sec with corresponding Reynolds numbers of 46,000 to 70,000. A stereo Particle Image Velocimetry (PIV) system was used to measure the wake of the MAV wing simultaneously with the signals from the twelve dynamic strain gauges mounted on the wing. With 20 out of 2400 Global Proper Orthogonal Decomposition modes, a reasonable estimation of the flow field was observed. Utilizing the simultaneously sampled strain gauges and flow field measurements in conjunction with modified Linear Stochastic Estimation, an estimation of the flow field with lower energy modes is reasonable. With these results, the methodology for estimating the wake flow field from just dynamic strain gauges is validated.