Numerical assessment of the vibration control effects of porous liners on an over-the-wing propeller configuration

Abstract

An over-the-wing position of propellers comes with noise shielding and significantly reduced sound emission to the ground. A drawback of this configuration may be the additional impact due to the passing propeller blades on the airfoil’s surface inducing structure-borne sound in the wing. This structural sound propagates within the wing and the fuselage and can radiate further into the cabin as airborne sound. In order not to trade the advantage of reduced noise transmission to the ground with higher sound pressure levels within the cabin, a remedy is proposed, which consists in placing a poroelastic liner on the wing’s surface below the rotor where the blade tips move closely to the airfoil’s skin. In this work, a numerical approach to assess the effects of porous liners for an over-the-wing propeller configuration is presented. A simplified generic channelwing structure is exposed to pressure fluctuations on its surface which are caused by an over-the-wing propeller. Porous liners are applied to the wing’s surface where the blade tips pass in close proximity. Structural vibrations are determined using the finite element method in frequency domain. Surface data is obtained from CFD computations. The porous material is represented by Biot’s theory.