NOx emission shows the maximum value at 25 per cent load when the engine operates along the marine characteristic curve, and NOx reduces in inverse proportion to increase of engine load. This tendency is similar in constant speed engine operation. This fact shows that it is possible to reduce E3 figure in light load operation without producing particulates by retarding injection timing.
7.Anti-vibration engine mounting.
While the main engine, generator engines and the propeller are to be a source of vibration and noise of ships, the main engine plays a large part in this issue. Until now, it has been considered that anti-vibration engine mount is possible only for medium or high speed engines and impossible for low speed engines, because vibratory frequency of low speed engine is low and resultantly vibratory torque is large. However, application of anti-vibration installation to low speed engine became possible recently since soft rubber for mounting engine can be designed and manufactured.
1) Engine vibration
When mounting the engine on anti-vibration foundation, vibrations in 6 degree of freedom system take places in directions of ahead-astern, port-starbord, up-down, rolling, pitching and yawing. Fig.11 shows vibration form of the engine.
