Efeito da variação da geometria do casco na resistência ao avanço e nos movimentos de uma barcaça regional

Abstract

The Amazon region has several inland navigation activities related to the transportation of cargo on river barges. However, there is still a lack of technical studies related to the hy drodynamic behavior of this type of vessel. In order to investigate the operational aspects of regional river barges, a comparative study was conducted, aiming to analyze several hydrodynamic characteristics of a regional barge hull. The effect of the change of the bow and stern hull inclination of a regional cargo transport barge on the hydrostatic characte ristics, ship resistance and motions was evaluated using simplified methods. Hydrostatic characteristics such as displacement, metacentric radius and height were analyzed. For the analysis of ship resistance, methods of practical use were evaluated (i.e., Holtrop and KR Barge), discussing the restrictions and limitations of each. Finally, the uncoupled motions of heave and pitch in regular waves were analyzed. For comparison purposes in each of these topics, a reference barge case was modeled, changing the inclination of the bow and stern of the hull, totaling four case studies. To perform the analysis, the soft ware Maxsurf and its utility packages Modeler, Resistance and Motions were used in the analysis of hydrostatics, ship resistance and motions in waves. Regarding the hydrostatic characteristics, study case 2 (inclination of 30° in the bow and 48° in the stern) and study case 4 (12° bow and 14° stern) presented better performance in relation to the standard case (17° bow and 21° stern), presenting a variation of 7.13% in cross-sectional metacen tric height for case 4 and -6.21% for case 2. Similarly, in the analysis of ship resistance using the method of Holtrop, case 2 presented variations between 13.7% and 39.3% and the case 4 variations between -6.7% and -25% in relation to the standard case. The KR Barge method overestimated the reference ship resistance values due to its limitations for practical implementation. For the significant accelerations in heave motion, study case 3 (14° bow and 17° stern) showed a variation of 2.17% and case 4 (12° bow and 14° stern) a variation of 4.56% with respect to the reference case, both operating at a speed of 1 knot. With the results obtained regarding river barges, it is expected that the work will add to the research on inland navigation in the Amazon region.