Water depth effect

Wind & Water Structural Analysis
1

Dear all,

I studied the three turbines NREL 5 MW, IEA 15 MW, and IEA 22 MW under the same metocean data, and I studied the effect of water depth (10 m- 20 m-30 m). I compare the effect considering DLC 1.1 and DLC 6.1 from IEC 61400-3 on mudline shear force and bending moment , here is my results. I don’t know why I feel that the results of IEA 15 MW are odd in shear force only and NREL 5 MW and IEA 22 MW are fine.
my questions are:
1-is there any reason that IEA 15 MW doesn’t follow the same regularity of the other turbine? or Did I something wrong for IEA 15 MW?
2- Why the effect of water depth is much in case of cut out wind speed more than rated wind speed, despite that the maximum forces are at rated wind speed?
3- why in case of parking and operation under rated wind speed the effect of water depth is more in moment that shear force and in case operation under cut out wind speed the opposite?
the increase in mudline reactions because of the water depth effect.

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Regards,
Marwa

2

Dear @Marwa.Mohamed,

I’m not sure I really understand the data you are sharing or what concerns you have with it. Are you plotting increases with respect to means, standard deviations, or maximums? You are comparing 3 water depths, but only show one value? Can you plot the data so that it is easier to see what concern you have with the trends?

Also, how are you changing the water depth? Are you changing the monopile design for each depth?

Best regards,