شناسایی ضرایب هیدرودینامیکی برای مدل شبیه سازی مانور یک کشتی ماهیگیری

The results of numerical and experimental investigations on the manoeuvring performance of a fishing vessel, typical for Mediterranean Sea, are here presented. PMM experiments were used for evaluating hydrodynamic derivatives and implementing the theoretical model. The simulation model was validated, both with zig-zag and spiral experimental model tests results in still water and compared with Tribon Initial Design module results.

A safe ship with optimum hydrodynamic performance constitutes the major concern in ship research and design activity. Appealing to the concept of global safety the naval architect aims to obtain the optimum ship shape, which allows safe operation in given environmental conditions. Since the occurrence of dangerous situations may have undesirable or detrimental consequences, the critical situations should be carefully investigated and a deeper understanding of complex hydrodynamic phenomena is mandatory. Possible major accidents could be avoided by imposing certain restriction within operation procedures. In this respect, it is very important for the designer to use powerful hydrodynamic tools in order to investigate the ship performance and safety, starting with the initial design stage.

The theoretical and experimental results of this paper refer to a fishing vessel, typical for Mediterranean Sea. PMM experiments were used for evaluating the manoeuvring hydrodynamic derivatives and implementing the theoretical model. The manoeuvrability qualities of the ship in still water were investigated by means of numerical simulations and standard experimental model tests. The results are also compared with those provided by Tribon Initial Design module. The correlation between simulation code and experimental results is satisfactory. Less satisfactory is the correlation between the results provided by Tribon software on one hand and the experimental and simulation ones given by the proposed theoretical model except for the steady turning radius. The values of the advance, transfer, tactical diameter and overshoot angles provided by Tribon code are higher. The proposed nonlinear mathematical model (4) has 23 hydrodynamic derivatives which can be evaluated experimentally by using PMM tests. The derivatives Xu,XuuXu,Xuu and XuuuXuuu can be determined based on model resistance tests while View the MathML sourceXu˙ derivative is evaluated theoretically. The design importance of the experimental hydrodynamic derivatives is linked to the accuracy of the theoretical estimations and to the sensitivity of the proposed mathematical model. Table 8 presents a ranking of the influences of the hydrodynamic derivatives on the standard manoeuvres parameters as tactical diameter, advance, transfer, overshoot angle, rate of heading from spiral tests and stability criterion. The main conclusions of the survey are as follows: