タグボート推進器後流による曳引力減少に関する一検討-II : 浅水域の模型実験

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We have well known that the towing force of a tugboat decreases because of a reaction of the jet stream caused by tugboat propeller. At present, this fact has not yet been taken into account in the estimation of towing force. It is the reason that the influence of the jet stream on the towing force is not examined exactly and systematically and also series data on the reduction of towing force are not shown. In this paper, the change of the towing force reduction relating to the depth-draft ratio was studied experimentally. Model experiments were carried out using a water-tank and a pair of ship models, namely a VLCC model and a tugboat model. And the VLCC model was moved laterally by the tugboat model. We obtained following results; (1) The analytic example of the effective towing force ratio in shallow water was shown based on experimental data. (2) The influence on the effective towing force by tow line length didn't appear clearly in shallow water. This is quite difference from it in deep water. (3) The laterally moving equation of motion used for analysis in deep water could not be adopted in shallow water.
2003-09-25