I am currently looking at the force distribution along the blade of the NREL 5MW turbine. The model is set to work at rated and steady conditions of 11.4m/s and 12.1rpm, and ran both ElastoDyn and BeamDyn with AeroDyn15. I plotted FN and FT using, respectively:
“B1N1Fn, B1N2Fn, B1N3Fn, B1N4Fn, B1N5Fn, B1N6Fn, B1N7Fn, B1N8Fn, B1N9Fn”
“B1N1Ft, B1N2Ft, B1N3Ft, B1N4Ft, B1N5Ft, B1N6Ft, B1N7Ft, B1N8Ft, B1N9Ft”
Making sure that N9 is in fact the last node of the mesh.
As found in literature (but please correct me if I’m wrong anywhere in this post) I would have expected the forces to peak at around 0.8-0.9R, and drop close to zero in proximity of the blade tip. Instead, as shown below:
NO tip loss: the forces in FAST decrease only just slightly (but not as much as I thought they would)
INCLUDING tip loss: FT increases instead of dropping, and peaks at the tip
Similar plots are obtained with forces on the rotor plane, Fx and Fy. Could you explain this behaviour?
Many thanks for your help.