Aerothermoelastic effects on a clamped-free-clamped-free panel experiment

Abstract: The experimental design of hypersonic wind tunnel experiments is dictated by the flow properties and duration of the target facility. Short-duration facilities do not afford the opportunity of aerothermal heating, and consequently, this absent heating needs to be emulated or induced. This heat may be induced via a heater to bring the model to a target temperature prior to the experimental run, or it may be emulated by using a different, typically softer, material without heating to replicate the mechanical turn-down that would be present with heat. This lack of heating leads to a different aerodynamic state, even if the structure is near equivalent. For compliant structures, this may be a problem, particularly if there is an aerodynamic-source instability. In this paper, a clamped-free-clamped-free model is assessed using the flow properties of the University of Southern Queensland's facility. Four cases were assessed as combinations of either a 300 K or 623.15 K fluid-side boundary condition, or a 300 K or 623.15 K structural-side material stiffness condition. From the results of coupled, aerothermoelastic simulations there were differences between all cases being assessed, particularly with the hotter material temperature cases exhibiting larger deflections. Despite causing greater aerodynamic forces, the hot wall reduced oscillation amplitude. Consequently, the greatest amplitudes of oscillation were observed for the hot material, cold wall. In a modal sense, the wall temperature had minimal effect on mode participation with a slight increase in higher-order mode contribution. Ultimately, the material temperature was the determining factor for deflection and so heating is value-add, but not a necessity. Keywords: Hypersonics, Aerothermoelasticity, Panels, CFD, Experimental aerodynamics, Experimental design