Experimental and Numerical Investigation of Aerodynamic Performance of Airfoils Fitted with Morphing Trailing-edges

Abstract

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 Experimental and numerical studies to characterize the aerodynamic and aeroacoustic performance of a simple NACA 0012 airfoil fitted with various morphing flaps have been successfully carried out. The airfoil was tested with various flap configurations having different camber profiles with a flap deflection angle of β = 10• . Comprehensive aerodynamic measurements including lift and drag forces, wake flow and pressure distribution over a wide range of angles of attack and chord-based Reynolds numbers were carried out. A detailed Detached Eddy Simulation has been performed for two angles of attack α = 0• and 4• and two types of flaps to further investigate the airfoil's flow behaviour and the noise generation mechanism. The experimental and computational results show that the camber profiles of the morphing flaps significantly affect the aerodynamic and aero-acoustic performances. Flow measurements showed that the downstream wake development can also be influenced as a result of changing the flap profile. It was found that highly cambered flap profiles provide higher lift coefficients and increased maximum lift coefficient compared to moderately cambered profiles while the lift-to-drag ratio slightly decreases. Contour plots using iso-surfaces of Q-criterion show that the separation near the trailing-edge is further delayed at high angles of attack for airfoils with highly chambered morphing flap. The far-field noise was calculated using Curle's analogy and it showed an increased noise for highly cambered flap, which corresponds to the increased pressure distribution, turbulence and wall-spectral levels. This study shows that the effective design space of the morphing flaps 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.

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

“…Ai et al [19,20] tested the aerodynamic and aeroacoustic performance of novel morphed flaps using Xfoil-BPM model. The results from these studies were then used to design the morphed flap camber profiles and further experimental and computational studies [10][11][12] were carried out. In the current study, NACA 0012 airfoil with morphed flap profiles (see Fig.…”

“…In the current study, NACA 0012 airfoil with morphed flap profiles (see Fig. 1b) having the lowest C L (Hinged Flap, HF) and highest C L (Morphed Flap, MF) from the previous studies [10][11][12] were used to further understand the aerodynamic, aeroacoustic and wake turbulence characteristics of the airfoils fitted with morphed flap.…”

“…As such, airfoil self-noise has been considered as an important component of airframe noise during take-off and landing. Some of the currently employed passive methods for airfoil trailing edge noise reduction includes serrated trailing edges [3,4], porous surface treatments [5][6][7][8] and morphing trailing edges [9][10][11][12]. With the use of morphing surfaces our aim is to address transition delay, separation postponement, lift enhancement, drag reduction, turbulence augmentation and noise suppression [13].…”

“…Most of the studies showed much interest on than the morphing structures and mechanism [14][15][16][17][18][19][20] than the aerodynamic and aeroacoustic performance. An innovative trailing-edge morphing mechanism that uses a honeycomb core with axial variable stiffness developed by Ai et al [19,20], was used as morphing profile for the experimental and computational studies carried out by Jawahar et al [10][11][12]. The recent study Jawahar et al [12] showed that small changes in the flap camber profile of the morphed flap can change the aerodynamic behaviour significantly.…”

Airfoil Trailing-edge Noise Reduction using Flow Suction

“…For Passive flow control approach, no external energy is added to alter the boundary layer. The changes to the flow characteristics are introduced by adding devices like serrations [2][3][4][5], types of riblets, morphing [6][7][8][9][10] or by applying porous [11][12][13] and compliant materials. whereas, for the active flow control method [14] external energy is added to the flow.…”