Conference Paper Low speed flutter and post-critical behaviour of flat plate and NACA0018 section models in a wind tunnel

Amandolese, Xavier

This paper explores the post-critical behaviour of two-degree-of-freedom flat plate and NACA0018 section model undergoing coupled-mode flutter in a wind tunnel. Tests are performed at moderate Reynolds number Re approximately 1 - 8×10(exp 4) using an aeroelastic set-up that enables high amplitude pitch-plunge motion without nonlinear structural limitations. For both models, two aeroelastic configurations have been studied: for a centre of rotation at the first quarter chord and for a centre of rotation at the mid-chord. Each configuration exhibits self-limited oscillations du to nonlinear aerodynamics saturation beyond the critical velocity. However, limit cycle oscillations (LCOs) evolution versus the reduced velocity highlight strong different behaviours between the flat plate and the NACA0018 model, along with a significant impact of the position of the elastic center. For the flat plate model two LCOs branches have been found in the post-critical regime. The first one is reached increasing the velocity beyond the coupled-mode flutter critical velocity and the second one occurs when the LCOs amplitude in pitch enter the stall region. This second LCO branch is then associated to a symmetric stall flutter regime. For the flat plate model the switch to symmetric stall flutter has only been observed for the configuration with the elastic axis at the mid-chord. For the NACA0018 model two LCOs branches have also been observed but the dynamical responses are also significantly impacted by a pure pitch instability that can be attributed to the motion-induced dynamics of a laminar separation bubble at moderate Reynolds number.
Meeting Information: First International Symposium on Flutter and its Application (May 15-17, 2016. Mielparque-tokyo), Minato-ku, Tokyo, Japan
Physical characteristics: Original contains illustrations
形態: 図版あり

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