Manoeuvring behaviour of push convoys: sub report 9. Additional verification of Class Va Vessel
Villagómez, J.; Delefortrie, G.; Verwilligen, J.; Mostaert, F. (2018). Manoeuvring behaviour of push convoys: sub report 9. Additional verification of Class Va Vessel. Version 2.0. FHR reports, 15_001_9. Flanders Hydraulics Research: Antwerp. VII, 23 + 18 p. app. pp. https://dx.doi.org/10.48607/348
Part of: FHR reports. Flanders Hydraulics Research: Antwerp, more
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Document type: Project report
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| Keywords |
Harbours and waterways > Manoeuvring behaviour > Open water
Simulations
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| Author keywords |
Unsteady turning circle; Yaw rate evolution; Model calibration |
| Authors | | Top |
- Villagómez, J., more
- Delefortrie, G., more
- Verwilligen, J., more
- Mostaert, F., more
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| Abstract |
This report describes the verification of the fast simulations for the Peche Melba (CEMT-) Class Va vessel. The discussion is based on results of steady and unsteady turning circle manoeuvres, performed with fast simulations. Available experimental data of captive tests are used to compare the results of fast time simulations. The analysis was focused on unsteady manoeuvres and in the transition from negative to positive velocities.
It was shown in previous reports that unsteady turning circle fast simulations show suddenly a drop in yaw rate near the change of sign of advance velocity from negative to positive[3]. Verification shows that the progression in tactical diameter on the steady turning circle manoeuvre was affected for the coefficient tuning performed to correct strange behaviour on the evolution of unsteady turning circles.
It is demonstrated that the yaw rate dropping is generated by a drastic drop on the propeller horizontal moment (Np). The propeller moment drop rises due to a rapidly crossing of the beta angle from the fourth to the fist quadrant on the NP coefficient table. In some cases, the values on the first quadrant near the limit of fourth quadrant are relatively high. This produces undesirable jumps and discontinuities on the transition from negative to positive speed. It is verified by using the experimental captive tests that in all cases the thrust predicted by the model was underestimated in the fourth quadrant. It was detected, as well, that in some cases the transversal rudder force during simulation was almost zero. This because the factor (1 + aH) that multiplies the transversal component was almost zero.
A proposal to correct these issues is presented and a preliminary fast time simulation set of standard manoeuvres is performed. |
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