## Structural loads at pitch and yaw actuator

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Younes.Oudich
Posts: 32
Joined: Fri Oct 02, 2020 2:44 am
Organization: self
Location: Belgium

### Re: Structural loads at pitch and yaw actuator

Dear Jason,

I'm coming back to what Pablo said about NacYIner, YawSpr and YawDamp numerical values. For NacYIner, it's NacYIner=2.60789E+06 kg.m^2 right? As for YawSpr and YawDamp, should we take the default values in the documentation which are :
9.02832E+09 YawSpr - Nacelle-yaw spring constant (N-m/rad)
1.916E+07 YawDamp - Nacelle-yaw damping constant (N-m/(rad/s))

Or take the values that respect the 3Hz natural nacelle frequency and a ratio damping of 0.02, as calculated by Pablo, which are:
9.2660e+08 YawSpr - Nacelle-yaw spring constant (N-m/rad)
1.9663e+06 YawDamp - Nacelle-yaw damping constant (N-m/(rad/s))

Or can we adjust the YawSpr and YawDamp freely with respect to 3Hz and a ratio damping of 0.65 for instance, which will be:
9.2660e+08 YawSpr - Nacelle-yaw spring constant (N-m/rad)
6.3905e+07 YawDamp - Nacelle-yaw damping constant (N-m/(rad/s))

Kindest regards

Younes

Jason.Jonkman
Posts: 5763
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

### Re: Structural loads at pitch and yaw actuator

Dear Younes,

As I explained to Pablo, the value of YawIner he was using in those equations was too small. YawIner in those equations should use the combined inertia from the nacelle (NacYIner) and the rotor about the yaw axis (YawIner = NacYIner + RotorInertiaAboutYawAxis). For the NREL 5-MW turbine, the value I used was NacYIner = 2,607,890 kg m^2 and YawIner = 25,410,000 kg m^2. I had used ζ = 0.02, but you could use a higher damping ratio of ζ = 0.65 if you want.

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov

Younes.Oudich
Posts: 32
Joined: Fri Oct 02, 2020 2:44 am
Organization: self
Location: Belgium

### Re: Structural loads at pitch and yaw actuator

Dear Jason,

Thank you for the reply, it helps a lot!

Kindest regards

Younes

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