CPPの単独効率を用いた船体粗度増加量の実務上の推定法

概要

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When the product of hull efficiency, mechanical efficiency and relative rotative efficiency do not almost change by marine foul extent, the variation of propulsive efficiency is nearly equal to that of propeller efficiency. Therefore, the difference of effective horse power is obtained by using the propulsive (presumed) efficiency between two performance curves on the same propeller condition and shipspeed. Furthermore the increased roughness of hull is calculated by THE DIFFERENCE. As the trial of the ship installed CPP may be practiced with propeller revolution constant and pitch angle stepped up and η_h×η_r is nearly constant with hull condition, the curve on the condition of foul propeller and clean hull is simply and practically presumed from the curve of clean conditional performance before service and the frictional power of roughend propeller on service. The result was made sure with the shipspeed trials on propeller revolution constant. And the increased roughness of hull was calculated so that the values were 9.35mm in Oct., 1982, 2.41mm in Oct., 1983 and 0.27mm in Oct., 1984.
社団法人日本航海学会の論文
1985-09-20