Aerodynamic and aeroacoustic performance of airfoils with morphing structures

TLDR

Shape optimization of airfoil surfaces, including morphing trailing edges, can improve load distribution and reduce noise generation. The study investigates the aerodynamic and aeroacoustic performance of airfoils with morphing trailing edges using a coupled structure/fluid/noise model. A NACA 63‑418 airfoil equipped with a conformal, internally‑mechanism‑free morphing flap made from a zero‑Poisson’s‑ratio honeycomb core was modeled with finite elements, allowing chordwise bending‑stiffness tailoring that controls flap deflection and noise, and its aeroacoustic behavior was predicted with a semi‑empirical airfoil noise model. Results show that the morphing flap reduces trailing‑edge noise across a wide range of speeds and angles of attack, and that tailoring the morphing profile further improves aerodynamic and aeroacoustic performance. © 2015 John Wiley & Sons, Ltd.

Abstract

Abstract Aerodynamic and aeroacoustic performance of airfoils fitted with morphing trailing edges are investigated using a coupled structure/fluid/noise model. The control of the flow over the surface of an airfoil using shape optimization techniques can significantly improve the load distribution along the chord and span lengths whilst minimising noise generation. In this study, a NACA 63‐418 airfoil is fitted with a morphing flap and various morphing profiles are considered with two features that distinguish them from conventional flaps: they are conformal and do not rely on conventional internal mechanisms. A novel design of a morphing flap using a zero Poisson's ratio honeycomb core with tailored bending stiffness is developed and investigated using the finite element model. Whilst tailoring the bending stiffness along the chord of the flap yields large flap deflections, it also enables profile tailoring of the deformed structure which is shown to significantly affect airfoil noise generation. The aeroacoustic behaviour of the airfoil is studied using a semi‐empirical airfoil noise prediction model. Results show that the morphing flap can effectively reduce the airfoil trailing edge noise over a wide range of flow speeds and angles of attack. It is also shown that appropriate morphing profile tailoring improves the effect of morphing trailing edge on the aerodynamic and aeroacoustic performance of the airfoil. Copyright © 2015 John Wiley & Sons, Ltd.