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QTF calculation back to each sea state + MCF and KAY less strick
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- Basically reverted commit 49079c9. I had moved the QTFs to be computed before solving for the different sea states, but this can be achieved by precomputing the QTFs with a previous RAFT run and using that as if the QTFs were computed from WAMIT. So, the QTFs are back to being computed for each sea state. This is more computationally expensive, but more versatile. The user have both options and can decide which one they prefer.

- MacCamy-Fuchs correction and Kim and Yue correction (MCF for second-order) are less strict now. They just required the member to be cylindrical. It can be inclined, tapered, or submerged. Clearly, they work worse for cases that are far from the original hypothesis of a vertical surface piercing circular cylinder.
- Moved Kim and Yue correction to member class
- Output name for the QTFs and RAOs now include Case and head in the name

We still need to include the mean drift for the second-order force component due to the quadratic acceleration.
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lucas-carmo committed Mar 22, 2024
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122 changes: 74 additions & 48 deletions examples/OC3spar-WAMITQTF.yaml → examples/OC4semi-slenderBodyQTF.yaml
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type: input file for RAFT
name: 5MW with OC3-Hywind spar
name: 5MW with OC4-DeepCWind semi-sub


settings: # global Settings
min_freq : 0.00025 # [Hz] lowest frequency to consider, also the frequency bin width
max_freq : 0.40 # [Hz] highest frequency to consider
max_freq : 0.25 # [Hz] highest frequency to consider
XiStart : 0 # sets initial amplitude of each DOF for all frequencies
nIter : 10 # sets how many iterations to perform in Model.solveDynamics()

Expand All @@ -16,20 +16,22 @@ site:
shearExp : 0.12 # shear exponent

cases:
keys : [wind_speed, wind_heading, turbulence, turbine_status, yaw_misalign, wave_spectrum, wave_period, wave_height, wave_heading ]
keys : [wind_speed, wind_heading, turbulence, turbine_status, yaw_misalign, wave_spectrum, wave_period, wave_height, wave_heading, current_speed, wave_gamma ]
data : # m/s deg % or e.g. 2B_NTM string deg string (s) (m) (deg)
- [ 0, 0, 0, operating, 0, JONSWAP, 10, 6, 0 ]
- [ 0, 0, 0, operating, 0, constant, 0, 5, 0, 0, 0]




turbine:

mRNA : 350000 # [kg] RNA mass
IxRNA : 35444067 # [kg-m2] RNA moment of inertia about local x axis (assumed to be identical to rotor axis for now, as approx) [kg-m^2]
IrRNA : 26159984.0 # [kg-m2] RNA moment of inertia about local y or z axes [kg-m^2]
xCG_RNA : 0 # [m] x location of RNA center of mass [m] (Actual is ~= -0.27 m)
hHub : 90.0 # [m] hub height above water line [m]
Fthrust : 800.0E3 # [N] temporary thrust force to use

I_drivetrain: 318628138.0 # full rotor + drivetrain inertia as felt on the high-speed shaft <<< not correct! <<<

nBlades : 3 # number of blades
Expand All @@ -41,9 +43,9 @@ turbine:
aeroServoMod : 1 # 0 aerodynamics off; 1 aerodynamics on (no control); 2 aerodynamics and control on

env:
rho : 1.225 # air density [kg/m^3]
mu : 1.81e-05 # air dynamic viscosity
shearExp: 0.2 # shear exponent
rho : 1.225 # air density [kg/m^3]
mu : 1.81e-05 # air dynamic viscosity
shearExp : 0.2 # shear exponent

blade:
precurveTip : 0.0 #
Expand Down Expand Up @@ -1014,7 +1016,6 @@ turbine:




pitch_control: # NOTE: these values from IEA 15 - not updated for NREL 5 MW yet
GS_Angles: [0.08951732571568687, 0.11113133201402342, 0.12982917355231283, 0.1466420801733839, 0.16211366466881905, 0.17655839335287876, 0.19019635501633186, 0.2031735797715147, 0.2155988980768675, 0.22755610891787487, 0.23910432007046029, 0.25029505429019794, 0.261175108296815, 0.2717701141434908, 0.2821130743895577, 0.2922299908966622, 0.30213155066939196, 0.3118425748263288, 0.32137789704483055, 0.3307503670667345, 0.3399699865577445, 0.3490461860239008, 0.3579880322509144, 0.3668047339186282, 0.37550289814624044, 0.3840890078940221, 0.3925675520014984, 0.4009446279452681]
GS_Kp: [-1.3577105502989462, -1.2022843685437077, -1.0708549194177244, -0.9582630743745694, -0.8607297095205451, -0.7754232092569442, -0.7001800303510133, -0.6333186502486411, -0.5735124113109392, -0.5197005998242658, -0.47102498684717165, -0.42678371240552293, -0.3863972240349146, -0.3493827470593987, -0.3153348933114633, -0.2839107527034031, -0.25481830344353146, -0.22780730986914496, -0.20266210648191768, -0.17919582739515136, -0.1572457543239439, -0.13666953808436225, -0.11734210805288207, -0.09915312775509398, -0.0820048872139108, -0.06581054702303714, -0.05049266752014871, -0.035981970477687836]
Expand Down Expand Up @@ -1059,105 +1060,130 @@ turbine:
#cap_d_in : [ ] # [m] inner diameter of internal structures (0 for full cap/bulkhead, >0 for a ring shape)



platform:

min_freq_BEM : 0.03 # [Hz] lowest frequency and frequency interval to use in BEM analysis
dz_BEM : 3.0 # [m] axial discretization panel length target for BEM analysis
da_BEM : 2.0 # [m] azimuthal discretization panel length target for BEM analysis
potSecOrder : 2 # [int] master switch for computing second-order wave forces; 0=do not compute, 1=compute QTFs using slender body approximation, 2=read QTF file in WAMIT format (.11d or .12d)
qtfPath : './examples/oc3_hywind.12d' # path to the qtf file for the platform
potModMaster : 1

yaw_stiffness : 98340000.0 # [N-m/rad] additional yaw stiffness to apply if not modeling crowfoot in the mooring system
potSecOrder : 1 # [int] master switch for computing second-order wave forces; 0=do not compute, 1=compute QTFs using slender body approximation, 2=read QTF file in WAMIT format (.11d or .12d)
min_freq2nd : 0.040 # [Hz] minimum frequency for second-order wave forces
df_freq2nd : 0.008 # [Hz] frequency step for second-order wave forces
max_freq2nd : 0.350 # [Hz] maximum frequency for second-order wave forces
outFolderQTF : './examples' # Output folder for storing the QTFs computed by RAFT. Written in .12d format.


members: # list all members here

- name : center_spar # [-] an identifier (no longer has to be number)
type : 2 # [-]
rA : [ 0, 0, -120] # [m] end A coordinates
- name : main_column # [-] an identifier (no longer has to be number)
type : 2 # [-] (1=turbine, >1=substructure, for now)
rA : [ 0, 0, -20] # [m] end A coordinates
rB : [ 0, 0, 10] # [m] and B coordinates
shape : circ # [-] circular or rectangular
gamma : 0.0 # [deg] twist angle about the member's z-axis
potMod : True # [bool] Whether to model the member with potential flow (BEM model) plus viscous drag or purely strip theory

MCF : True
# --- outer shell including hydro---
stations : [-120, -12, -4, 10 ] # [-] location of stations along axis. Will be normalized such that start value maps to rA and end value to rB
d : [ 9.4, 9.4, 6.5, 6.5] # [m] diameters if circular or side lengths if rectangular (can be pairs)
t : 0.027 # [m] wall thicknesses (scalar or list of same length as stations)
Cd : 0.8 # [-] transverse drag coefficient (optional, scalar or list of same length as stations)
Ca : 1.0 # [-] transverse added mass coefficient (optional, scalar or list of same length as stations)
# (neglecting axial coefficients for now)
CdEnd : 0.6 # [-] end axial drag coefficient (optional, scalar or list of same length as stations)
CaEnd : 0.6 # [-] end axial added mass coefficient (optional, scalar or list of same length as stations)
rho_shell : 8500 # [kg/m3]

stations : [-20, 10 ] # [-] location of stations along axis. Will be normalized such that start value maps to rA and end value to rB
d : [ 6.5, 6.5] # [m] diameters if circular or side lengths if rectangular (can be pairs)
t : 0.03 # [m] wall thicknesses (scalar or list of same length as stations)
Cd : 0.56 # [-] transverse drag coefficient (optional, scalar or list of same length as stations)
Ca : 0.63 # [-] transverse added mass coefficient (optional, scalar or list of same length as stations)
CdEnd : 0.6 # [-] end axial drag coefficient (optional, scalar or list of same length as stations)
CaEnd : 1.0 # [-] end axial added mass coefficient (optional, scalar or list of same length as stations)
rho_shell : 7850 # [kg/m3] material density
# --- handling of end caps or any internal structures if we need them ---
# (These will only be *within* the inner diameter of the outer shell, so they don't interrupt the outer shell.)
cap_stations : [ -20 ] # [m] location along member of any inner structures (in same scaling as set by 'stations')
cap_t : [ 0.03 ] # [m] thickness of any internal structures
cap_d_in : [ 0 ] # [m] inner diameter of internal structures (0 for full cap/bulkhead, >0 for a ring shape)


- name : offset_column # [-] an identifier (no longer has to be number)
type : 3 # [-] (1=turbine, >1=substructure, for now)
rA : [ 28.86 , 0, -20] # [m] end A coordinates
rB : [ 28.86 , 0, 12] # [m] and B coordinates
heading : [ 60, 180, 300] # [deg] heading rotation of column about z axis (for repeated members)
shape : circ # [-] circular or rectangular
gamma : 0.0 # [deg] twist angle about the member's z-axis
potMod : True # [bool] Whether to model the member with potential flow (BEM model) plus viscous drag or purely strip theory
MCF : True
# --- outer shell including hydro---
stations : [-20, -14, -14, 12 ] # [-] location of stations along axis. Will be normalized such that start value maps to rA and end value to rB
d : [ 24, 24, 12, 12] # [m] diameters if circular or side lengths if rectangular (can be pairs)
t : 0.06 # [m] wall thicknesses (scalar or list of same length as stations)
Cd : [0.68, 0.68, 0.61, 0.61] # [-] transverse drag coefficient (optional, scalar or list of same length as stations)
Ca : [0.4, 0.4, 0.63, 0.63] # [-] transverse added mass coefficient (optional, scalar or list of same length as stations)
CdEnd : 2.3 # [-] end axial drag coefficient (optional, scalar or list of same length as stations)
CaEnd : 0.7 # [-] end axial added mass coefficient (optional, scalar or list of same length as stations)
rho_shell : 7850 # [kg/m3] material density
# --- ballast ---
l_fill : [52.9, 0.0, 0.0] # [m]
rho_fill : [1800.0, 0.0, 0.0] # [kg/m3]

l_fill : [5.0418, 0, 7.77] # [m]
rho_fill : [1025.0, 0, 1025.0] # [kg/m3]
# --- handling of end caps or any internal structures if we need them ---
# (These will only be *within* the inner diameter of the outer shell, so they don't interrupt the outer shell.)
cap_stations : [-120 ] # [m] location along member of any inner structures (in same scaling as set by 'stations')
cap_t : [ 0.2 ] # [m] thickness of any internal structures
cap_d_in : [ 0 ] # [m] inner diameter of internal structures (0 for full cap/bulkhead, >0 for a ring shape)
cap_stations : [ -20, -14, -14, 12] # [m] location along member of any inner structures (in same scaling as set by 'stations')
cap_t : [ 0.06, 0.06, 0.06, 0.06 ] # [m] thickness of any internal structures
cap_d_in : [ 0 , 12, 0, 0 ] # [m] inner diameter of internal structures (0 for full cap/bulkhead, >0 for a ring shape)

# temporarily removed bracing members <<<


mooring:
water_depth: 320 # [m] uniform water depth
water_depth: 200 # [m] uniform water depth

points:
- name: line1_anchor
type: fixed
location: [853.87, 0.0, -320.0]
location: [418.8, 725.38, -200.0]
anchor_type: drag_embedment

- name: line2_anchor
type: fixed
location: [-426.935, 739.47311, -320.0]
location: [-837.6, 0.0, -200.0]
anchor_type: drag_embedment

- name: line3_anchor
type: fixed
location: [-426.935, -739.47311, -320.0]
location: [418.8, -725.38, -200.0]
anchor_type: drag_embedment

- name: line1_vessel
type: vessel
location: [5.2, 0.0, -70.0]
location: [20.434, 35.393, -14.0]

- name: line2_vessel
type: vessel
location: [-2.6, 4.5033, -70.0]
location: [-40.868, 0.0, -14.0]

- name: line3_vessel
type: vessel
location: [-2.6, -4.5033, -70.0]
location: [20.434, -35.393, -14.0]

lines:
- name: line1
endA: line1_anchor
endB: line1_vessel
type: main
length: 902.2
length: 835.5

- name: line2
endA: line2_anchor
endB: line2_vessel
type: main
length: 902.2
length: 835.5

- name: line3
endA: line3_anchor
endB: line3_vessel
type: main
length: 902.2
length: 835.5

line_types:
- name: main
diameter: 0.09
mass_density: 77.7066
stiffness: 384.243e6
diameter: 0.0766
mass_density: 113.35
stiffness: 753.6e6
breaking_load: 1e8
cost: 100.0
transverse_added_mass: 1.0
Expand Down
28 changes: 10 additions & 18 deletions examples/example-slenderBodyQTF.py
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Expand Up @@ -7,33 +7,25 @@
import os.path as path

# open the design YAML file and parse it into a dictionary for passing to raft
flNm = 'OC3spar-SlenderBodyQTF'
flNm = 'OC4semi-slenderBodyQTF'
with open('./examples/' + flNm + '.yaml') as file:
design = yaml.load(file, Loader=yaml.FullLoader)

# Create the RAFT model (will set up all model objects based on the design dict)
model = raft.Model(design)
model = raft.Model(design)

# Evaluate the system properties and equilibrium position before loads are applied
model.analyzeUnloaded()

# Compute natural frequencie
model.solveEigen()

# Simule the different load cases
# Due to the linearization of the quadratic drag term in RAFT, the QTFs depend
# on the sea state specified in the input file.
# If more than one case is analyzed, the outputs are numbered sequentially.
# Two output files are generated:
# - The QTF, following WAMIT .12d file format. File name is qtf-slender_body-total_Head#p##[email protected]
# - The RAOs used to computed the QTFs, following WAMIT .4 file format.
# The #p## in the file name indicates the wave heading in degrees and @ is used to differentiate
# between different cases.
model.analyzeCases(display=1)

# Plot the power spectral densities from the load cases
model.plotResponses()

# Visualize the system in its most recently evaluated mean offset position
model.plot(hideGrid=True)

# Save the response to a given output folder
outFolder = './examples/'
model.saveResponses(path.join(outFolder, flNm))

plt.show()

# 0.02
# 12.37
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