Studies on Handling Conditions of Marine Engine for Minimizing Oil Consumption―II Operation with Low Pitch Angles of CPP

摘要

A motor ship with CPP which controls the angular pitch of propeller blades according to the change in hull resistance of water, can sail at the most economic condition for the main engine and the propeller. A series of experiments on a marine engine operation was made at low load runnings of 7-12mile/hour, in success of the last report (Nishiya, et al., 1984). The following results were obtained on effects of various combination of n and θp for saving fuel oil on various running conditions. i) Multiple regressions of V and Gm by n, θp and S V=0.0182・n-0.0506・S+0.7225・θp-8.4928 Gm=0.01491・n+0.16123・V²+0.5419・S-1.8963・θp+27.182 Where, V is running speed in mile/hour, Gm fuel oil consumption in kg/mile, n rate of rotation of main engine in rpm, Op pitch of propeller blades in degree and S slip ratio of propeller. ii) The operating horse power of main engine (Nℯ) can instantly be given in enough accuracy for practical use by the following experimental formulae. θp=12°:Nℯ=15.0373・Te-0.1821・h-2235 θp=13°:Nℯ=35.5033・Tℯ-0.6289・h-4670 θp=14°:Nℯ=59.5652・Tℯ-1.1581・h-7728 Where, Te is exhaust gas temperature of main engine in ℃ and h rate of rotation of turbo-charger in rpm. iii) When Nℯ is 500 PS or less, a greater θp brings a smaller specific fuel oil consumption (bℯ) in g/PS/hour.