8/9/2019 FM&L_Assignment TriFloater v01 -Exploded View

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MSc Advanced Mechanical Engineering 1/5

SEEA

AIM

Department of Energy

MSc Advanced Mechanical Engineering

Fluid mechanics and Loading

Assignment: Preliminary hydrostatics and hydrodynamics of a floating wind turbineconfiguration

Figure 1: Dutch TriFloater !1"

The aim of this assignment is to assess the hydrostatic and hydrodynamics characteristics of a Tri!loater

su""ort structure for a 5 M# offshore floating wind turbine$

DES#$I%TI&'%t is "ro"osed to use the configuration shown in !igure & and !igure '( consisting of a floating su""ort

structure )in red in !igure 1*( and a tower( a drive train and a rotor )in white in !igure 1*$

The draft of the structure is e+ual to d$

The floating su""ort structure is com"osed of: three columns of radius RC(

having foot"lates of radius RFP )the added mass can be calculated using the added mass coefficientcm( relative to the volume of a s"here of the same radius as the foot"late( minus the volume of acolumn section of heightRC(

three lowest bracings of diameter dbA( with ,- vertical "osition above the .eel e+ual to VCGbA(

a series of secondary bracings( the dec. and the basement of the tower( with a dis"laced volume e+ualto Vothers( a vertical "osition of the , e+ual to VCBothers

!loating su""ort structure

0otorrive train

Tower

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there are three ballast tan.s( one in each column( which can be filled with seawater( with diameter dBTand bottom located at height hBT above the column bottom$

The su""ort structure )foot"lates( columns( lowest bracings( secondary bracings( dec. and tower basementincluded( ballast tan.s e2cluded* has a mass e+ual to mSS and a vertical "osition of the ,- from the .eel e+ual

toVCG

SS.

The tower( the drive train and the rotor total mass )turbine mass* is e+ual to mtur( with a vertical "osition of the,- from the .eel e+ual to VCGtur$The wind turbine generates a ma2 inclining moment e+ual to MI$

)aria*le Description )alue u+m+

g -ravitational acceleration 3$41 m/s&

rhosw Seawater density 1&5 .g/m'

,E&MET$-

d raught 1& m

dbA 6owest bracing diameter & m

dT iameter of ballast tan. '$4 m

hT istance between the bottom of the column ).eel*

and the bottom of the ballast tan.

$&& m

6,, istanced between the columns7 centres 84 m

0, ,olumn radius 9 m

0!P !oot"late radius 3 m

others olume dis"laced by others submerged elements of

su""ort structure

99$9; m'

,-bA ,- of lowest bracing )from .eel* & m

,others ertical "osition of , of the others submerged

elements )from .eel*

&$5 m

I'E$TIAL

cm !oot"late added mass $89

mSS Su""ort structure mass 115 .g

mtur Turbine )rotor

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.&$/ %$&,$AMMEThe assessment re+uires the following wor. "rogramme:

1* #rite an E2cel s"read sheet to calculate:

a$ Total volume and mass dis"laced

1$ Total olume ? 0otor volume < rive train volume < Tower volume < !loating su""ortstructure volume

&$ Total mass? 0otor mass < rive train mass < Tower mass < !loating su""ort structure mass

b$ @ydrostatic stability analysis )( M( -( -M( restoring moment M0*( considering also theloss of stability if necessary1$ uoyancy force ! !Matural fre+uency in heavee$ Bsing the ballast system( can the static inclination angle be reduced to CeroD

&* Present the results of your assignment as a short written re"ort )ma2 15 "ages "lus a""endi2es* toinclude:

a$ %ntroduction

b$ ,alculations / >otes

c$ ,onclusions and additional considerations )see +uestion '*

d$ Tables )A""endi2*

e$ !igures )A""endi2*

'* Are there any other considerations that you feel are im"ortantD #hat are the limitations of the current

a""roachD

N.B.

All the calculations "resented in the written re"ort should be fully develo"ed )from the definition tothe final literal e2"ression( substituting numbers only at the end*( and a re"ort "resenting only the finalnumbers will be negatively mar.ed( even if the results are e2act$

Please use the a2is system of reference "resented in !igure & and !igure '( and use the variable namesshowed$ Bsing a different system and different variables will result in a "enalty in the final mar.$

Always s"ecify unit of measures$

,larity and correct English s"elling are two of the criteria considered for the mar.$

!or correct terminology( "lease refer to htt ":/ /www$it tcwi.i$org/

http://var/www/apps/conversion/tmp/scratch_6/%5Chhttp://var/www/apps/conversion/tmp/scratch_6/%5Chhttp://var/www/apps/conversion/tmp/scratch_6/%5Ch

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MA$/ #$ITE$IA

APP0A,@ A> ,A6,B6AT%>S ;5F

o Bse of right definitiono ,orrect final literal e2"ression

o ,orrect final valueo ,orrect and clear gra"h

,>,6BS%>( ,MME>TS A> 6%M%TAT%>S 1&$5F

,6A0%TG A> STG6E 1&$5F

o erivation of literal e2"ressiono Englisho 0es"ect of conventionso ,larity

$EFE$E'#ES

H1I Bulder, B. H., M. Th Van Hees, A. Henderson, R. H. M. Huijsmans, J. T. G. Pierik, E. J. B. Snijders, G. H.Wijnants, and M. J. Wol. !Stud" to easi#ilit" o and #oundar" $onditions or loatin% oshore &ind tur#ines.!ECN, MARIN, TNO, TUD, MSC, Lagerway the Windmaster '())(*.

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0!P

y

dbA0,

2

6,,

Figure 0: TriFloater top vie2 !modified from 1"

C

yd dbA

0,

Figure 3: side vie2 !modified from 1"