Experimental study of hydroacoustics of flexible trailing edge

Resumo

© Proceedings of the 26th International Congress on Sound and Vibration, ICSV 2019. All rights reserved.This work has as main objective to analyse experimentally the influence of the effects of the flexibility in the sound emissions of trailing-edge extensions in aeronautical structures. For this, an experimental apparatus installed in a cavitation tunnel was used, whose working fluid is water. Flow was studied around a rigid NACA 0012 profile with interchangeable flexible trailing edge extensions. Two flat metal plates with different thicknesses were used as extensions, leading therefore to different values of flexural stiffness. The purpose of such tests is to obtain high Reynolds numbers, low Mach numbers and high fluid-structure loading factors (related to the ratio of fluid and solid densities). Which enhances fluid-structural interactions; acoustic effects are captured with a hydrophone installed in acoustic chamber in the section of tests. This analysis allows to make comparisons of the experimental results with predictions from aeroacoustic theory. Increasing the flexibility of the trailing edge, according to this theory, reduces aeroacoustic and hydroacoustic emissions. However, the experimental results obtained show the opposite effect: the more flexible trailing edge led to a greater sound radiation. The results suggest that there is significant changes in turbulence due to the effect of the trailing edge vibrations; a possible increase in turbulent kinetic energy due to surface vibration could explain the present results

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