I'm now doing a project in which a FEM and BEM (Blade Element Momentum) coupled simulation is conducted to study the aeroelastic coupling of a large wind turbine blade(NREL 5MW, with hub connection part). I built the model with Python scripting in Abaqus and for the aerodynamic part wrote a script to implement the classical BEM method (not unsteady BEM method). I divided the blade in several sections along the span. In one step of the method i called Xfoil to create the lift and drag coefficients for all the sectional aerofoils which have naturally different Renolds number, Mach number and angle of attack. As input airfoil for Xfoil i take the real coordinates of the profil which don't vary from 0 to 1. My questions are:
1. As input airfoil must the coordinates be normalized or is it also possible to read in real coordinates? Will the result be reliable for creating the coefficients when using the real unnormalized coordinates?
2. Suppose using the real coordinates, then which Renolds number should i specify, rho*vinf*actual chordlength/nu (the actual Renolds number) or rho*vinf*1/nu (the scaled one), which is using the normalized coordinates?
3. The input angle of attack to Xfoil is the angle between the incoming flow and the horizontal axis or the angle between the incoming flow and the chord length direction? say in my case the chordlength, which is reprensented by the coordiantes, doesn't lie in the horizontal direction.
Sorry for typing so long cuz I'm really a new bee with Xfoil. Any help from you guys would be appreciated.