Instructions to participants

- Summary
- Overview of cases
- Detailed Overview of cases
- Case 1.1: KVLCC2 Deep water, forces & moments
- Case 1.2: KVLCC2 Deep water, trajectories
- Case 2.1: KVLCC2 shallow water, forces & moments
- Case 2.2: KVLCC2 shallow water, trajectories
- Case 3.1: KCS Deep water, forces & moments
- Case 3.2: KCS Deep water, trajectories
- Case 3.3: KCS Waves, trajectories
- Case 4.1: KCS shallow water, forces & moments
- Case 4.2: KCS shallow water, trajectories
- Case 5.1: ONRT, forces & moments
- Case 5.2: ONRT, trajectories
- Case 5.3: ONRT Waves, trajectories

Case 5.3: ONRT Waves, trajectories

- Free running at model self propulsion point in calm water (mandatory)
- With propellers and rudders
- With bilge keels
- L
_{PP}= 3.147 [m], (model scale 1:48.935) - Radius of gyration for yaw and pitch 0.246L
_{PP}(in air) - Radius of gyration for roll 0.39B (in air)
- GM=2.068 [m] in full-scale (0.0423 [m] in model)
- Approach speed U
_{0}= 15.1 [kn] in full-scale (1.11 [m/s] in model) - Re∗=3.39×10
^{6}, Fr∗=0.20, g = 9.80665 [m/s^{2}] - Rudder rate 5.0 [deg/s] in full-scale (35.0 [deg/s] in model)
- Water depth: Infinity
- Regular waves
- Wave height (from top to trough) 63 mm on model scale, 3.08 m on full scale.
- Wave length to ship length ratio = 1.0, meaning that the wave frequency is 4.42 rad/s on model scale (0.633 rad/s on full scale). Consequently, the wave period is 1.42 s on model scale (9.93 s on full scale)
- Wave direction: head waves with the ship approaching at t=0
- The rudder execute (t=0) is when a wave crest is passing midship.

Fr∗: Nominal Froude number, the Froude number when ship runs in calm water with constant propeller rate of revolution.

All quantities are non-dimensionalized by desired approach speed (U

(1)

where g is the gravitational acceleration and ν is the kinematic viscosity.

Manoeuvre | Starting speed | |
---|---|---|

5.3 | 35° turning circle test, starting to portside | Fr = 0.20 (equivalent to 15.1 knots full scale) |

- All calculations are to be conducted for model scale conditions.
- All simulations results should be provided in the format described in section 4.
- The propeller rate of revolution should correspond to the self-propulsion point of the model. When the RPM is unknown (because for example a constant thrust or actuator disk model is used in CFD based simulations) please indicate this.
- Similar to the experiment, the rudders should be controlled by Equation (2) during approaching before starting rudder execution for starboard side zigzag.
- During the turning circle manoeuvre, the rudders should go to the real geometric 35 degrees (not 35 degrees away from the neutral angle).

- The trajectory and time histories of heave ¸ angular motions , dimensional velocities for 6DOF motions (u,v,w,p,q,r), rudder angle δ, and propeller rate of revolution n [rps] after the ship was released (t = t
_{0}), should be submitted. - The ship position or trajectory should be given in an Earth-fixed coordinate system with X pointing North, Y pointing East, and Z pointing downward as shown in Figure 1. This XY axis system remains horizontal in the earth. The ship was released at (X
_{0}, Y_{0}) when t = t_{0}. The roll angle (ϕ) is positive for pushing starboard into the water, pitch (θ) is positive for bow up position and yaw angle (ψ) is positive for bow turned to starboard. The reported trajectory is dimensional and angular motions should be reported in degrees. The angular velocities should be reported in degree second. The reported yaw angle should be the deviation of yaw angle respect to the target yaw i.e. ψ-ψ_{C}. - All velocities for 6DOF motions (u, v, w, p, q, r) should be reported in ship-fixed coordinate system with x axis positive toward bow, y axis positive toward starboard and z axis positive downward. This xyz axis system is body-fixed, which means it rotates with the ship in yaw and pitch and roll. Given this convention, the reported velocities are:

(3)

(4)

In Equation (4), the unit of , and is [deg/s]. - Rudder angle (δ) is positive when trailing edge moves to portside.
- All motions should be reported at O. The origin is located on O which is located at midships, the intersection of ordinate 10 the centre line plane and the still water waterline.

The submission consists of an excel file (example is given) with 19 columns and with rows for every time step. The time step is free to chose, but a small enough time step somewhere around 0.05 to 0.01 is recommended to get sufficient accuracy. The following quantities are asked:

Symbol | Item | Unit |
---|---|---|

t | time | s |

x | X position in earth fixed system | m |

y | Y position in earth fixed system | m |

z | Z position in earth fixed system | m |

ϕ | Roll angle | degrees |

θ | Pitch angle | degrees |

ψ | Yaw angle | degree |

u | surge velocity | m/s |

v | sway velocity | m/s |

w | heave velocity | m/s |

p | roll rate | deg/s |

q | pitch rate | deg/s |

r | yaw rate | deg/s |

δ | Rudder angle | deg |

n | Propeller revolutions of portside propeller | rpm |

There is a right-handed earth-fixed coordinate system x

Figure 1: Illustration of the sign convention of the earth-fixed and body-fixed coordinate system.

Figure 2: Example trajectory (bird-eye view) of Case 5.3,

Figure 3: Time traces of important signals for Case 5. 3; experimental values

Data reduction will take place to derive the quantities HD and μD:

For the time trace under consideration, these values are determined. To determine HD and μD and , the position difference between ψ=630° and ψ=990° is used..

Category | Unit | Validation Variables | EFD |
---|---|---|---|

[-] | Drift distance / L_{PP} (HD/L_{PP}) |
0.386 | |

[deg] | Drift direction (muD) | 112 |

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