| Budget Amount *help |
¥14,100,000 (Direct Cost: ¥14,100,000)
Fiscal Year 1985: ¥4,900,000 (Direct Cost: ¥4,900,000)
Fiscal Year 1984: ¥9,200,000 (Direct Cost: ¥9,200,000)
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| Research Abstract |
New marine propellers with improved cavitation performance were developed by using two-dimensional foil section design theory and lifting surface theory. Moreover, both calculation and experiment on propeller boundary layer and finite-span foil were performed as related research. The following conclusions were obtained.
1. In order to diminish cavity volume, propellers with flat pressure distribution were developed. The experiment using both the new and conventional MAU type propellers showed that cavity volume of the new propellers reduced to 1/2-1/3 of that of the MAU type one, and the fluctuating pressure became about half of that due to the MAU type one.
2. Since the load distribution of the propellers with the above-mentioned pressure characteristics becomes higher in the aft part of the blade section, the thrust becomes lower than the calculation unless carefully designed.
3. In order to stabilize sheet cavity, a propeller with triangular pressure distribution was developed when a M
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AU type propeller generates cloud cavitation. The cloud cavitation was not observed on the new propeller, and the paint test showed that the paint peeling off which was observed in thr case of the MAU type propeller was not observed.
4. A calculation scheme where target pressure distribution can be realized with relatively high accuracy was developed.
5. A theoretical calculation method of boundary layers on propeller blade was developed, using quasi-three-dimensional approximation. This method can be said very promising sinve the calculated results could show the difference of the propeller boundary layer characteristics observed in the experiment although quantitative agreement with the experiment is not sufficiently high in the present stage.
6. Adequacy of the concept of equivalent two-dimensional foil was verified from theoretical calculations on various finite-span foils. Moreover, some simple equations were proposed in order to obtain modified equivalent two-dimensional foil whose thickness is reduced than that of the equivalent two-dimensional one so as to make the calculation accuracy higher. Less
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