Aerodynamic and Aeroacoustic Performance of Airfoils Fitted with Morphing Trailing-edges

Abstract

Experimental and numerical studies of a simple NACA 0012 airfoil fitted with two different flap profiles were successfully carried out to characterize their aerodynamic and aeroacoustic performance. The airfoil was tested with two flap configurations with different flap camber and a flap deflection angle of β = 10 • . The aerodynamic lift and drag measurements show improved lift-to-drag performance for the morphed flap airfoil. Surface flow visualization has shown delayed separation for the morphed flap airfoil. Flow measurements showed that the downstream wake development can be significantly influenced by the flap profile. Particle Image Velocimetry was used to study the flow over the flap and airfoil wake. The tests were carried out for a flow velocity of U ∞ = 20 m/s, corresponding to a chord-based Re c = 2.6 × 10 5 . The mean velocity contours at the wake showed increased wake deficit and turbulent kinetic energy for the morphed flap airfoil compared to the hinged flap airfoil. The turbulent kinetic energy results displayed a characteristic double peak behavior which was also the dominant content of the streamwise normal Reynolds shear stress component. Large eddy simulations were carried out for the two airfoils and the results were validated with the experimental measurements. The boundary layer profile from the computations showed delayed separation. The wall pressure spectra close to the trailing edge showed increased energy for the morphed flap airfoil relative to the hinged flap airfoil. The Curle's acoustic analogy was used to calculate the far-field noise measurements and morphed flap airfoil showed increased noised compared to the hinged flap airfoil.

Flow characteristics of slat cove fillers

“…Several passive and active flow control methods have been investigated in the past to attenuate airframe noise, the methods include morphing structures [1][2][3][4][28][29][30][31], porous materials [5][6][7], surface treatments [8] and serrations [9].…”

Aeroacoustic Performance of High-lift Airfoil with Slat Cove Fillers

“…Even though the aircraft engine noise has been brought down substantially by the use of high bypass engines the airframe noise remains a major contributor to aircraft noise. In order to reduce these prominent noise sources several passive and active flow control methods have been investigated in the past it includes morphing structures [1][2][3][4][5][6][7], porous materials [8][9][10][11], surface treatments [12], serrations [13][14][15] and transverse jets [16]. The high-lift devices namely the slats and flaps are one of the major contributors to airframe noise.…”

Numerical Investigation of High-lift Airfoil Fitted with Slat Cove Filler

“…Large Eddy Simulation (LES) to investigate the unsteady flow characteristics of 30P-30N airfoil were carried out. The airfoil had a retracted chord length of c = 0.457 m. The simulations were carried out at an angle of attack 5.5 • for an inlet velocity of U = 58 m/s corresponding to a chord based Reynolds number of Re c = 1.71×10 6 . Preliminary steadystate CFD RANS simulations were carried out with k-ω S S T turbulence model and the validated results were used to initialize the LES simulation.…”

“…• at an inlet velocity of U ∞ = 58 m/s, corresponding to a chord-based Reynolds number of Re c = 1.71 × 10 6 . The steady and unsteady pressure measurements validate well with the experimental data available in the literature.…”

“…Introduction T HE introduction of high bypass-ratio turbofans engines into civil aircraft have drastically reduced engine noise over the last several decades, making the airframe noise the same magnitude as that of the engine noise, especially during the landing phase. In order to reduce these prominent airframe noise sources several fundamental passive and active flow control methods have been investigated over the recent years, such as, morphing structures [1][2][3][4][5][6][7], porous materials [8][9][10][11], surface treatments [12], serrations [13][14][15] and transverse jets [16]. One of the prominent sources of airframe noises are the high-lift devices namely the slats and flaps.…”