抄録
Recent extension of the container transport system has lead to the remarkable increase in both speed and size of container ships. Since there is a practical limitation to the maximum output of an individual engine, multiple-screw propulsion will become necessary for a large container ship to attain a higher speed with a large capacity of transport than the speed of 25 knots. Comprehensive research works have been conducted with the aim at developing a high speed container ship with triple-screw to be built at Mitsui Shipbuilding & Engineering Co., Ltd. in 1972, for the service between Europe and Japan.
This report deals with comparative tests among single-, twin- and triple-screw propulsions, and with mutual interference between the hull and propellers, cavitation researches and full-scale measurements on the triple screw ship. Such other items of research works as vibratory forces of the propellers will be reported in a later paper.
Principal conclusions obtained are as follows,
1) A triple-screw ship has a better propulsive performance than a twin-screw ship.
2) For the triple-screw ship adopted, inward rotation of the wing propellers gives better propulsive efficiency than outward rotation, which is explained both by the wake measurements by 5 hole pitot tubes and by the results of the self-propulsion tests.
3) Mutual interference between the center and wing propellers can be neglected practically.
4) The effect of variation of the load of a propeller on the self-propulsion factors of each propeller will be negligible, unless the variation is too large.
5) Added resistance of the appendages is also subject to the scale effect.
6) Decreasing the camber of the propeller section near the leading edge was shown to be an effective means to decrease the amount of back cavitation, both on the ship and on the model.
