How to apply a certain harmonic force to the foundation

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Yuanzhao.Han
Posts: 18
Joined: Thu Dec 08, 2016 4:43 am
Organization: Tianjin University
Location: China

How to apply a certain harmonic force to the foundation

Postby Yuanzhao.Han » Tue Apr 04, 2017 7:39 am

Dear Dr.Jason
I want to apply a certain harmonic force P=asinwt to the floating platform foundation.But I don't know how to operate in the software FAST V8 .I would be very happy if you could give me some guidance.
Best regards

Jason.Jonkman
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Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
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Re: How to apply a certain harmonic force to the foundation

Postby Jason.Jonkman » Tue Apr 04, 2017 10:40 am

Dear Yuanzhao.Han,

The use of regular (periodic) waves (WaveMod = 1) in HydroDyn will result in sinusoidal forcing of the floating foundation at the frequency of the regular wave.

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

Yuanzhao.Han
Posts: 18
Joined: Thu Dec 08, 2016 4:43 am
Organization: Tianjin University
Location: China

Re: How to apply a certain harmonic force to the foundation

Postby Yuanzhao.Han » Thu Apr 06, 2017 9:03 am

Dear Dr Jason
I carefully read the method you said. But I still have some doubts. Because your method is to simulate the regular wave to realize the harmonic force applied on the platform. But the harmonic force P=asinwt that I mentioned above is not generated from the wave, but from the vortex motion. So I would like to calculate the response of the platform in the condition that the floating wind power generator system is under the effect of the vortex force and wind load. From my point of view, the use of regular (periodic) waves (WaveMod = 1) in HydroDyn can not achieve what I want .
Best wishes

Jason.Jonkman
Posts: 3657
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: How to apply a certain harmonic force to the foundation

Postby Jason.Jonkman » Thu Apr 06, 2017 11:17 am

Dear Yuanzhao,

You first post you mention that you want to apply a harmonic load on the floating platform. Now, I'm not sure I understand enough about what load you want applied where to comment.

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

Yuanzhao.Han
Posts: 18
Joined: Thu Dec 08, 2016 4:43 am
Organization: Tianjin University
Location: China

Re: How to apply a certain harmonic force to the foundation

Postby Yuanzhao.Han » Fri Apr 07, 2017 8:49 am

Dear Dr Jason
Sorry, I didn't make it clear. I repeat my question. I would like to apply the wave forces and an additional harmonic force (P = asinwt) on the floating foundation . In this formula ,a and w have been already calculated by external program. What I want to know is how to add the harmonic force P in the FAST program. And if the original function of FAST 8 can not achieve it, whether I modify the FAST source code is a viable solution or not?
Best regards

Jason.Jonkman
Posts: 3657
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: How to apply a certain harmonic force to the foundation

Postby Jason.Jonkman » Fri Apr 07, 2017 9:20 am

Dear Yuanzhao,

Ah, now I understand. You'll need to make a small modification to the source code. I suggest you look in the HydroDyn source code to see how the constant load AddF0 is added to the platform load. You can add your new harmonic force at the same place in the source code and recompile FAST.

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

Yuanzhao.Han
Posts: 18
Joined: Thu Dec 08, 2016 4:43 am
Organization: Tianjin University
Location: China

Re: How to apply a certain harmonic force to the foundation

Postby Yuanzhao.Han » Sat Apr 08, 2017 7:58 am

Dear Dr Jason,

Thank you for your guidance. Then I'll try it your way.

Best regards


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