Experimental investigations on aerodynamic response of panel structures at high subsonic and low supersonic mach numbers

Panel flutter is an aeroelastic phenomenon known since the mid 1940's. Extensive experimental and theoretical studies followed in the 1960's and 70's. The theoretical models applied at that time yield satisfactory results for subsonic and high supersonic Mach numbers but are inaccurate in terms of predicting the aerodynamic loads at transonic flows. In the recent years new Fluid-Structure-Interaction (FSI) methods by means of coupled CFD and FE computations have shown an increased accuracy in that Mach number domain. Within a common research project of the Airbus Company and the German Aerospace Center (DLR) such a computational approach is used for theoretical panel flutter analysis. Experiments were performed in 2015 and 2017 to validate the numerical results and to study the flow characteristics in the Mach number range 0.7 < M∞ < 1.2. For this purpose the aerodynamic response on the first eigenmode of a clamped rectangular plate is measured by means of forced motion experiments. Hydraulic actuation is used to realize small sinusoidal deflections of the plate over a wide range of amplitudes and frequencies, which has been verified by a stereo camera marker tracking system. The flow conditions in the wind tunnel are varied by means of the Mach number and the total pressure (Reynolds number) and the flow response is measured by high sensitive miniature pressure transducers.