Tài liệu Lesson 10-Marine Diesel Engines (1) doc

Lesson 10-Marine Diesel Engines (1)

The technical term outfitting is relevant to a wide range of knowledge in the light of

the latest classification in the shipbuilding circle in Japan. In addition to ship outfitting,

which is dealt with in Ship Equipment, outfitting also concerns engine outfitting,

electricity outfitting and painting. From this lesson on, we shall come to learn the engine

outfitting.

It is known to all that the propulsion plant of a ship is often compared to one's heart

and the hull to one's body. In general, a propulsion plant will appear in four basic types,

namely, marine diesel engine, gas turbine engine, steam engine and atomic power, with

marine diesel engines most widely employed on board the ship. Therefore, emphasis is to

be put upon marine diesel engines.

Before we set to work on the detailed construction of diesel engine parts, we should

first know something about the several classes into which diesel engines may be divided.

It's quite O. K. for us to classify diesel engines in several ways. For example, according

to operating cycle, engines can be divided into two groups based on the number of piston

strokes per cycle, either four strokes or two strokes. Accordingly, there are respectively a

four-stroke cycle engine and a two-stroke cycle engine. The difference between them is

that a two-stroke engine ignites twice as often as a four-stroke engine.

Then two-stroke engines may be further classified by the methods used to supply an

engine with fresh air, i. e. crankcase scavenging or blower scavenging ( pump

scavenging ) : In consideration of scavenging ways we must not neglect another

two essential concepts, longitudinal ( uniflow) scavenge and transversal scavenge.