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. While 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.

General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms The aerodynamic performance and wake development of a NACA 0012 airfoil fitted with morphing trailing edges were studied using experimental and computational techniques. The NACA 0012 airfoil was tested with morphing trailing edges having various camber profiles with the same trailing edge tip deflection. The aerodynamic force measurements for the airfoil were carried out for a wide range of chord-based Reynolds number and angles of attack with trailing edge deflection angle of β = 5• and 10• . The experiments were validated with steady-state RANS simulation using SpalartAllmaras turbulence model. Experimental results show that the camber profiles of the morphing trailing edges significantly affect the airfoil's aerodynamic performance and effectiveness in improving the lift coefficient further by tailoring the morphing profiles. Hot-wire measurements showed that the downstream wake development can also be influenced as a result of changing the morphing trailing edge camber profile. It was found that highly cambered trailing edge profiles provide higher lift coefficients and increased maximum lift coefficient compared to moderately cambered profiles while the lift-to-drag ratio slightly decreases. Velocity contour plots show that the separation near the trailing edge is further delayed at high angles of attack for airfoils with highly chambered morphing trailing edge. This study shows that the effective design space of the morphing trailing edges can be expanded taking into account the optimal aerodynamic performance requirements. The study also suggests that in order to achieve optimum aerodynamic performance, independent surface morphing of the suction and pressure surface camber will be required to delay the onset of flow separation.

The aerodynamic performance of a NACA 0012 airfoil with morphing flaps were studied experimentally and numerically. Comprehensive aerodynamic measurements including pressure distribution, lift and drag forces and wake flow for airfoils with different morphing flap camber profiles were carried out over a wide range of angles of attack and chord-based Reynolds numbers. The results show that the morphing flap camber profiles significantly affect the aerodynamic performance and the downstream wake development. It was found that the highly cambered flap profiles provide higher lift coefficients compared to the moderately cambered flap profiles, with an insignificant reduction in the overall lift-to-drag ratio. Furthermore, the Q-criterion iso-surface results show