Morphing airfoils analysis using dynamic meshing

Abstract

Purpose -The purpose of this paper is to use dynamic meshing to perform CFD analyses of a NACA 0012 airfoil fitted with a morphing trailing-edge (TE) flap when it undergoes static and time dependent morphing. The steady CFD predictions of the original and morphing airfoils are validated against published data. The study also investigates an airfoil with a hinged trailing edge flap for aerodynamic performance comparison. The study further extends to an unsteady CFD analysis of a dynamically morphing trailing edge flap for proof-of-concept and also to realise its potential for future applications.Design/methodology/approach -An existing parametrization method was modified and implemented in a user-defined function (UDF) to perform dynamic meshing which is essential for morphing airfoil unsteady simulations. The results from the deformed mesh were verified to ensure the validity of the adopted mesh deformation method. ANSYS Fluent software was used to perform steady and unsteady analysis and the results were compared with computational predictions.Findings -Steady computational results are in good agreement with those from OpenFOAM for a non-morphing airfoil, and for a morphed airfoil with a maximum TE deflection equal to 5% of the chord. The results obtained by ANSYS Fluent show that an average of 6.5% increase in lift-to-drag ratio is achieved, compared with a hinged flap airfoil with the same TE deflection. By using dynamic meshing, unsteady transient simulations reveal that the local flow field is influenced by the morphing motion.Originality/value -An airfoil parametrization method was modified to introduce time dependent morphing and used to drive dynamic meshing through an in-house developed UDF. The morphed airfoil's superior aerodynamic performance was demonstrated in comparison with traditional hinged trailing edge flap. A methodology was developed to perform unsteady transient analysis of a morphing airfoil at high angles of attack beyond stall, and to compare with published data. Unsteady predictions have shown signs of rich flow features, paving the way for further research into the effects of a dynamic flap on the flow physics.

Analysis of a 3D Unsteady Morphing Wing with Seamless Side-edge Transition

“…Most studies to date have simplified morphing problems to static morphing, thereby overlooking the dynamic effects that deforming motion of the TEF might have on the flow field or its contribution to the airframe noise. Abdessemed et al [20,21] introduced a framework to study dynamically morphing airfoils by modifying a parametrization method to include time and integrating it in the commercial software ANSYS Fluent [22] with the help of a User-Defined Function (UDF). The same methodology was used for a 2D aeroacoustic study of a harmonically morphing TEF [23].…”

“…statically morphed), and a wing with a conventional hinged flap and unsealed side-edge gaps. Secondly, an extension to the work investigating the unsteady aerodynamic effects of a morphing wing ( [20,21]) will be proposed in order to study a dynamically morphing TEF with a seamless transition (where the TEF deforms from a baseline position to a final deflection). A modified transition function will be used to model the transition between the static and morphing part of the wing.…”

“…For the present problem, two parametrization methods are required. The TEF deformation is parametrized using the modified method [20] (1) where wte is the value of maximum deflection at the TE, T is the morphing period and xs is the start location for the morphing (75% for the subsequent studies).…”

Aerodynamic Analysis of a harmonically Morphing Flap Using a Hybrid Turbulence Model and Dynamic Meshing

“…The effects of periodic forcing using a NACA 0012 airfoil fitted with a harmonically oscillating TEF on the aerodynamic performance are investigated. All test cases used an airfoil with a chord c = 0.2286 m, a Reynold number based on the chord Re = 0.62×10 6 and Mach number of 0.115.The deformation of the TEF was parametrized using a modified method of the unsteady approach introduced in [17], then the method was adapted so that the entire range of motion could be achieved. The thickness distribution of the NACA 0012 wing was added to a parametric definition of the wing (Eq.1) which allows the control of the portion morphed, the amplitude of the oscillation and its frequency.…”

“…Both methods demonstrated the aerodynamic superiority of a morphing TEF compared to the hinged flap, however, the experiments showed a reduction of the aerodynamic efficiency of the morphing TE flap at angles of attack closer to the stall. Abdessemed et al [16,17] expanded on the study of Woods et al [14] by introducing time dependency in the parametrization method of the FishBAC [14] and analyzed the unsteady morphing of an airfoil equipped with a morphing TEF. However, only the downward deflection was considered, and the low fidelity unsteady RANS with kω-SST turbulence model was used.…”