Katrien Eloot St. John s

Transcription

1 VALIDATION OF SHIP MANOEUVRING IN SHALLOW WATER THROUGH FREE- RUNNING TESTS Katrien Eloot St. John s

2 Overview Introduction Free-running and captive model tests Mathematical models Validation at model scale Conclusions

3 Introduction Estimated turning circles in shallow water on pilot cards and wheelhouse posters International workshops and projects SIMMAN SimVal Verification and validation Model tests Numerical methods Full scale trials

4 Free-running and captive model tests KVLCC2, benchmark ship FHR data set for shallow water manoeuvring prediction 300 captive tests per draft and UKC (four quadrant, large drift) FHR and MARIN data set for SIMMAN 97 captive tests (one quadrant, drift angle < 12 degrees) at FHR Free-running tests at MARIN and FHR SC 75 Scale L OA m L PP 320 m B 58 m D 30 m T F m T A m T M m VOL m³ C B 0.81 Propeller Max rpm 100 Dp m P/Dp AEP Rudder A R m²

5 Free-running and captive model tests Tank and carriage characteristics Dimensions Bottom Release mode UKC KVLCC2 UKC 1 80 UKC 2 50 UKC 3 20 Institute L W h max h/t h Bottom accuracy [m] [m] [m] [-] [m] [% of UKC] % MARIN % FHR %

6 Free-running and captive model tests Partial turning circle at FHR (40 degrees) and MARIN (90 degrees) - uncertainty analysis with 10 repeated tests Not completed turning circle at FHR Zigzag manoeuvre 10/2.5 and 20/5 (larger reliability)

7 Free-running and captive model tests +10/-2.5 zigzag Large scatter for both test facilities -20/+5 zigzag Rate of turn 0, Run 3 Large repeatability

8 Mathematical models MARIN FHR 4 DOF modular model 3+1 DOF modular model Database Slender body and cross flow for hull form Model per UKC Model tests Model tests Model per UKC

9 Validation at model scale SIMMAN: Verification and Validation of Ship Manoeuvring Simulation Methods with focus on model scale validation SimVal: Sea Trials and Model Tests for Validation of Shiphandling Simulation Models with focus on full scale validation Especially in shallow water, more insight is required to obtain comparable results at model scale.

10 Validation at model scale: turning circle 1080 degrees turning circles with pull-out manoeuvres (FHR) Predictive power of the simulation models for decreasing h/t Drawbacks: Large difference PS/SS Drop down of the speed at 50% and 80% UKC Starboard side Port side h/t = 1.2, PS h/t = 1.2, SS h/t = 1.5, PS h/t = 1.5, SS h/t = 1.8, PS h/t = 1.8, SS Strong link between test program and model formulation

11 Lateral distance [m] Validation at model scale: turning circle Longitudinal distance [m] Free-running model tests (FRMT) FHR, FRMT, Run 3 FHR, FRMT, Run 4 MARIN, FRMT, Run 1 FHR, PMM MARIN, EMP Prediction simulation models

12 Rate of turn [deg/s] Validation at model scale: turning circle No overshoot in the simulation models of FHR and MARIN Prototype Time [s] Overshoot in the free-running model tests of FHR and MARIN FHR, FRMT, Run 3 FHR, FRMT, Run 4 MARIN, FRMT, Run 1 FHR, PMM MARIN, EMP

13 Rate of turn [deg/s] δ/ψ [deg] 15 Validation at model scale: zigzag manoeuvre +10/-2.5 Phase shift / asymmetry in PS and SS for PMM simulation model Prototype Time [s] More course stable behaviour in simulation Prototype Time [s] FHR, FRMT, rudder angl FHR, FRMT, course ang MARIN, FRMT, rudder a MARIN, FRMT, course a FHR, PMM, rudder angle FHR, PMM, course angle MARIN, EMP, rudder an MARIN, EMP, course an FHR, FRMT MARIN, FRMT FHR, PMM MARIN, EMP

14 Rate of turn [deg/s] δ/ψ [deg] Validation at model scale: zigzag manoeuvre -20/+5 Smaller phase shift (time range of 20 seconds) than +10/-2.5 zigzag Prototype Time [s] Prototype Time [s] FHR, FRMT, rudder angle FHR, FRMT, course angl MARIN, FRMT, rudder an MARIN, FRMT, course an FHR, PMM, rudder angle FHR, PMM, course angle MARIN, EMP, rudder ang MARIN, EMP, course ang Smaller overshoot angles in simulation compared to FRMT FHR, FRMT MARIN, FRMT FHR, PMM MARIN, EMP

15 Conclusions Prediction of manoeuvring behaviour of ships in shallow water is important Validation at model scale before validation at full scale could be a must Availability of captive and free-running model tests Accuracy of tank facility and test procedure Influence of tank walls Release mode of FRMT 10/2.5 zigzag: 2.5 degrees, small angle for decision rudder execute Small difference in FRMT results at FHR and MARIN with KVLCC2 (with slightly different propeller)

16 Conclusions Prediction of manoeuvring behaviour of ships in shallow water is important Validation at model scale before validation at full scale Availability of captive and free-running model tests Turning circle: PMM based simulation model: better prediction but problem with speed drop EMP based simulation model overestimates Zigzag manoeuvre: results of 20/5 better than 10/2.5, but a more course stable behaviour is predicted

17 Conclusions Prediction of manoeuvring behaviour of ships in shallow water is important. No satisfactory result for the validation at model scale, further examination of model testing and mathematical modelling Better understanding of the steady or transient behaviour of the water flow in the tank, see also promissing results of flow predictions from RANS calculations using CFD techniques. Further collaboration must be encouraged.