Experimental Study on Accelerating and Decelerating Ship Motions

概要

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In this report, the accelerating and decelerating motion of ship are estimated from a practical point of view, using the following equation, (m+mx) Vs=T (1-t) -R At first, the added mass of the model ship (mx) is measured by forced surging test. Next, operating the propeller, the forced surging test is carried out, and it is shown that both the model ship thrust T and the thrust deduction factor (1-t) are almost independent on acceleration of ship but on Js (=Vs/nD). Therefore the right hand side of the above equation may be regarded as a function of ship speed Vs and the propeller revolution n. By this reason, the results of the propeller characteristics and the thrust deduction factor, obtained by a kind of behind test of constant speeds, can be used to estimate the accelerating and the decelerating ship motions. At last, putting mx, T and (1-t) into the above equation together with the resistance test result R and integrating numerically, the velocities during the accelerating and the decelerating motions are estimated. Comparing these results with those of the free running experiments, they are in good coincidence. Some comments are also mentioned, as to the effective braking force and the side force acting on a ship hull at the initial stage of stopping.
社団法人日本船舶海洋工学会の論文