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AdaptFoil2D

AdaptFoil2D is a code developed in CENER for 2D airfoil aeroelastic modelling based on a potential solution. The aerodynamic part is based on panel methods, numerical approximations employed to represent the aerodynamic behaviour of airfoil geometries. Basically, panel methods comprise the discretization of the geometry into panels and the distribution of singularity elements (sources, vortices or doublets). This set of singularities must fulfil the non-penetration condition on a discretization of the airfoil surface. Apart of the airfoil geometry, the wake modelling is based on vortex methods to complete the general picture of airfoil and flow. The current version of AdaptFoil2D is developed taking into account a good balance between accuracy and computational effort for aerodynamic modelling, with the following characteristics:

  • Surface panel code for a thick airfoil section.
  • The wake is a doublet panel attached to the TE, transformed into discrete vortices downstream.
  • A free wake and a direct time-stepping method are used to calculate the wake roll-up.
  • The time marching solution is also used for the aerodynamic and structural coupling with direct application of the dynamic motion equations.

In addition to attached flow, separated flow is considered using a double wake approach. The separation point of the airfoil is prescribed as a function of the angle of attack. The unsteady aerodynamic performance in separated flow conditions and the dynamic stall occurrence are simulated including some engineering concepts based on the Beddoes-Leishman model.

Regarding the structural part, the dynamic motion of the airfoil is mainly based on a rigid body motion. The mass and moment of inertia are assumed to be at a single point of the mean line, where a 3-degrees of freedom system of springs and dampers is coupled simulating the structural properties of the real blade section. Furthermore, the implementation includes an approximation for passive deformations of the LE and TE regions, using a static Euler-Bernoulli beam model with a suitable value of the bending stiffness EI.

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