Blade Tip-brake Model in OpenFAST

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MoeMoe.Aye
Posts: 2
Joined: Sun Sep 08, 2019 12:56 pm
Organization: University of Rostock
Location: Germany

Blade Tip-brake Model in OpenFAST

Postby MoeMoe.Aye » Tue Sep 10, 2019 4:43 am

Hi Everyone,

I’ld like to implement a rotating tip brake for a variable speed stall-regulated small wind turbine in OpenFAST v2.1.

Roughly speaking, the tip-brake model looks like this https://isaacbrana.files.wordpress.com/2010/07/passive-control-of-tip-blade-using-screw-on-tip-shaft-and-spring1.jpg . A centrifugal force is pre-defined to activate the rotor tip brake. This centrifugal force causes the blade tip segment to rotate 90° in high wind conditions especially when the rotor exceeds its rated rotational speed.

According to Guide to Changes in FAST v8 and this discussion https://wind.nrel.gov/forum/wind/viewtopic.php?t=2123, I understand that the tip-vane type of tip brake was developed only in FAST v7 and was not further developed in OpenFAST. Is this the one described in section 3.1 of this document,, Investigation of Aerodynamic Braking Devices for Wind Turbine Applications"? In the case of the rotating tip-brake model, what would be the most viable way to implement it in AeroDyn or ServoDyn? Does anyone have an experience with this kind of blade tip-brake model in FAST v8 or OpenFAST ? I would greatly appreciate any suggestion.

Best regards,
Moe Moe

Jason.Jonkman
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Location: Boulder, CO
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Re: Blade Tip-brake Model in OpenFAST

Postby Jason.Jonkman » Tue Sep 10, 2019 6:44 am

Dear Moe Moe,

NREL has still not been funded to implement a tip brake into FAST v8 or OpenFAST. I'll let others on the forum comment if they've developed something.

The tip-brake model of FAST v7 and older was a very simple model that could likely be tailored to model the braking of any type of tip-brake device, at least at a global level. A more sophisticated tip-brake model is likely warranted if you want to model the details of a specific tip-brake device.

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

MoeMoe.Aye
Posts: 2
Joined: Sun Sep 08, 2019 12:56 pm
Organization: University of Rostock
Location: Germany

Re: Blade Tip-brake Model in OpenFAST

Postby MoeMoe.Aye » Tue Sep 10, 2019 9:12 am

Dear Jason,

Thank you very much for your quick reply. I really appreciate it.

Jason.Jonkman wrote: The tip-brake model of FAST v7 and older was a very simple model that could likely be tailored to model the braking of any type of tip-brake device, at least at a global level. A more sophisticated tip-brake model is likely warranted if you want to model the details of a specific tip-brake device.


It helps me better understand the tip-brake model developed in FAST v7.


Best regards,
Moe Moe


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