Hi all,

I am currently working on a BEM code to calculate optimal twist distributions for the NREL 5MW. I am working off the data provided in the report:

‘Definition of a 5-MW Reference Wind Turbine for Offshore System Development’

But in Figure 9-1 there is a graph of rotor speed vs wind speed for steady state conditions and I was just wondering if anyone had the corresponding data points for that graph?

Thanks very much.

Sam

Dear Sam,

A tabular listing of the values contained in Figure 9-1 of the NREL 5-MW specifications report is contained in the attached text file.

Best regards,

WindSpeedRelationships.txt (2.27 KB)

Dear Jason,

Thank you very much for the response.

I also have one more question which might be a bit odd, referencing to the curve of Rotational Speed vs Wind Speed. Basically why is it that shape? Is it a design choice? Also why does it reach maximum rotational speed at rated wind speed? As for a smaller turbine I have seen the curve reaching maximum rotational speed at a much lower wind speed compared to rated. Sorry if that question doesn’t make much sense but I’m just generally wanting to know about why the curves might start or increase from minimal or start to level off at maximum at the wind speeds they do.

Thanks very much

Sam

Dear Sam,

Actually, due to Region 2.5, the NREL 5-MW turbine does reach a rotor speed near its maximum at a wind speed below rated (about 10.2 versus 11.4 m/s). As mentinoed in the NREL 5-MW specifications report that you referred to in your first post above, Region 2.5 is included to limit tip speed (and hence noise emissions) at rated power.

Best regards,

Thank you again for your reply.

Dear

I’m sorry. I have a question about the RotSpeed (Initial or fixed rotor speed (rpm)) in the inputfile XXX.fst of FAST.

I don’t understand why to set the Initial or fixed rotor speed. Because we have had the actual wind speed.

Is there some impacts to the loads of wind turbine such as out-of-plane bending at the root of blade.

Thank you very much.

---------------------- INITIAL CONDITIONS --------------------------------------

0.0 OoPDefl - Initial out-of-plane blade-tip displacement (meters)

0.0 IPDefl - Initial in-plane blade-tip deflection (meters)

0.0 TeetDefl - Initial or fixed teeter angle (degrees) [unused for 3 blades]

0.0 Azimuth - Initial azimuth angle for blade 1 (degrees)

12.1 RotSpeed - Initial or fixed rotor speed (rpm)

0.0 NacYaw - Initial or fixed nacelle-yaw angle (degrees)

0.0 TTDspFA - Initial fore-aft tower-top displacement (meters)

0.0 TTDspSS - Initial side-to-side tower-top displacement (meters)

Yiqing XIA

Dear Yiqing,

We set initial conditions such as rotor speed at the beginning of the simulation so that the turbine is as close to equilibrium as possible. Otherwise it takes much longer to get past the start-up transients as the turbine tries to settle down.

Marshall

Dear Marshall

Thank you very much for the reply.