LIMIT CYCLE OSCILLATION OF A PLATE WITH PIEZOELECTRIC ELEMENTS IN SUPERSONIC FLOW
Fluid structure interaction of an elastic plate with piezoelectric elements, turbulent freestream flow at Mach 2.5, and a pressurized cavity is investigated computationally and correlated with a recent experiment. The pressure field on the surface of the plate is measured using pressure sensitive paint and the structural response is observed using the measured voltage of a piezoelectric patch. The pressure and structural response are investigated in terms of frequency content and amplitude variation over time. The measurements show a dominant frequency of oscillation which indicates the likely onset of flutter and a post-flutter limit cycle oscillation (LCO). A computational investigation is conducted to study the effects of static pressure differential, temperature differential, cavity pressure coupling, and plate boundary conditions on the linear flutter onset condition and the nonlinear post-flutter LCO characteristics. Rivets that connect the plate to the supporting structure are modeled as local constraint in the in-plane direction and their effect on the nonlinear stiffness is investigated. The measured plate natural frequencies outside of the wind tunnel are shown to be closer to pinned than to clamped boundary conditions. Computations show that the coupling between the cavity acoustic and plate structural modes is necessary for flutter onset in the wind tunnel conditions. Direct correlation between computed and measured aerodynamic pressure shows reasonable agreement in amplitude and frequency. Computational results are obtained using Piston Theory and also potential flow aerodynamics, which is more appropriate for the reduced frequency on the order of 1 considered in this work. Lastly, computed and measured pressure LCO mode shapes are extracted and correlated using the spectral proper orthogonal decomposition1
