# problem with AeroDYn 15

Dear Jason
I think i have a problem with AeroDyn 15. in this relation, i have two questions.

1. Are Rotor aerodynamic power coefficient and power coefficient same values? if they are, with WT-PERF, i found that maximum power coefficient for WP-1.5MW is 0.5 but in simulations, sometimes it is over than 0.55. what is the problem?
2. I use the equation (cp=RotPwr1000/((1/2)rhopiR^2*v^3)) and in this time, power coefficient exceeds than 0.6.
i will be so grateful for your answer

Best Regards,

I’m sorry, but I don’t really understand your questions. Please clarify.

Best regards,

Dear Jason

I am really sorry for my English!!. I need power coefficient for my simulations in FAST V8. So i use rotor aerodynamic power coefficient (RtAeroCp)‌‌‌ in AeroDyne. Although i know that it must not exceeds 0.5 but sometimes it is more than 0.55. Now i want to ask is RtAeroCp the same as power coefficient or something else?
Another question is, i use rotor power(RotPwr) in ElastoDyn for obtaining power coefficient by this relation:
cp=RotPwr1000/((1/2)rhopiR^2*v^3)
where rho is air density, R is rotor radius and v is wind velocity
this time it is more than 0.6, what is the problem?

Best regards