| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1991: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1990: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
Measurements and Analysis were carried out regarding pressure fluctuation on hull surface just above a propeller and propeller cavitation phenomena by the use of a actual ship "Fukae-marul", which is a training ship of Kobe University of Mercantile Marine, and has the displacement 762tonnes, the length between perpendiculars 45m, and a 4-bladed skewed and controllable pitch propeller with diameter 2.1m.
1 A stroboscope synchronized with propeller revolution and a video camera were mounted on the outside hull near propeller. Experimental voyages were carried out in nighttime and in clear water area of the Kii Channel, and succeeded in recording cavitation phenomena.
2 The data of pressure fluctuation were also successfully obtained at various conditions of propeller revolution and blade angle. There have been reported so far a very little data regarding actual ship equipped with a CPP. The data obtained here, therefore, can be considered to be-very valuable.
3 Pressure fluctuation is great
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ly influenced by cavitation in both of amplitude and frequency. As for frequency, main component is equal to blade frequency when cavitation does not occur, while the 2nd and 3rd modes of blade frequncy become dominant components as cavitation occurs and glows.
4 Because of being two variables of revolution and blade angle, the influence of CPPship on cavitation characteristics is not so simple as that of FPP-ship. The analysis could have found that blade attack angle could be a possible variable to be able to unify the influences of both variables mentioned above.
5 There have been so far several methods which estimate the propeller surface force taking into consideration of cavitation effects. Three of them examined about their validities. It was revealed that these conventional methods are valid, though ia a limited extent, for FPP-ship. For CPP and/or skewed propeller, however, all of them are not valid.
It would be a future task to develop new estimation method being adaptable not only for FPP but also for CPP and skewed propeller. Less
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