| Summary: | 碩士 === 國立臺灣海洋大學 === 系統工程暨造船學系 === 98 === This thesis is a part of the continuous research for the four-bladed cupped propellers with area ratio 0.75 to find suitable amounts of cup having good efficiency and being able to avoid bubbles cavitation erosion for propeller operating at speed about 40 kn at inclined shaft condition. The cup at 0.7R of the first propeller is 37% of the maximal thickness. The cup at 0.7R of the second propeller has the same ratio as the first one. However, the thickness at 0.7R of the second propeller is increased 14％ and at 0.25R is increased 18％ compared with the first one in order to meet the strength requirement for operating at speed 40 kn.
From the experimental results, it is shown that the thicker cupped propeller has better efficiency and the bubbles cavitation concentrates on the near of the tailing edge. However, the face cavitation of the thicker cupped propeller appears strongly when the propeller operating at high advance ratio for 0.5 cavitation number at inclined shaft condition. That means the amount of cup seems unsuitable to increase anymore. Besides, the increase of chord length at root improves the cavitation phenomena at root significantly.
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