Dear Sudhakar,
Just a few comments/questions:
- How are you plotting the tangential force in N, when AeroDyn outputs this force in N/m? Have you someone integrated the distributed force to lump the forces at nodes?
- It appears from your input files that blade/turbine structural flexibility, shaft tilt, the skewed-wake correction, and unsteady airfoil aerodynamics are still enabled for this simulation, which will result in a time-variation of aerodynamic loads. Have you time-averaged this time variation in order to generate your plot?
- How are you considering the blade deflection in your integration of aerodynamic forces when hand-calculating the aerodynamic torque? How does this hand calculation compare to the aerodynamic torque computed and output by AeroDyn (RtAeroMxh)?
- We’ve improved the blade-element/moment theory (BEMT) algorithm, as well as the hub- and tip-loss models in the release of AeroDyn v15.04–see e.g. FAST v8 "Mach number exceeds 1.0" for some wind cases - #15 by Jason.Jonkman. It would be interesting to see how your results change if you upgrade to the newest version of AeroDyn. Regardless, I would not expect the aerodynamic loads to be exactly zero at the tip, as the tip chordlength is finite–and while the axial induction factor tends toward 1 at the tip, the tangential induction factor tends toward zero (and thus there is still dynamic pressure at the tip).
Best regards,