Английский язык: Сборник текстов и упражнений для студентов специальности "Эксплуатация судовых энергетических установок". Писарева Л.П. - 20 стр.

     VI. Answer the questions to the text.
     1. What are the basic systems of introducing the fuel charge into the cylinder?
     2. How long does combustion continue?
     3. What can you tell about the time of introduction the fuel.
     4. What is the amount of oil controlled by?
     5. What can the spray valve have?

      VII. Tell some words about fuel injection system.




                                 Lesson 6 A. Burning the Fuel

                                       Diesel combustion

      Conditions for good combustion must be proved because the diesel engine has to handle
the entire job of mixing and igniting fuel inside the cylinder in an extremely short time. Suc-
cessful combustion depends on the following conditions:
      a) fine atomization
      b) high temperature for prompt ignitor
      c) high relative velocity between fuel and air particles
      d) good mixing of fuel and air.
      Atomization and spreading of the fuel depend largely on the injection system. Com-
pression ratio, cylinder dimensions and cooling arrangements determine the temperature
conditions.
      Mixing depends on proper relation of the injection pattern, the intake system and the
shape of the combustion space formed by the cylinder head, the cylinder walls and the piston
crown.
      There are different types of combustion chambers. The main of them are:
      1) direct injection;
      2) precombustion chamber;
      3) turbulance chamber
      Direct – injection Engines. – Most of the solid – injection engines turning at less than
400 r.p.m. and many running at higher speeds employ direct injection, that is, the oil is sprayed
directly into the clearance space of the cylinder. The spray valve has from 5 to 10 orifices, of
about 0.01 to 0.002 in diameter. This separation of the oil charge gives the necessary diffusion
and insures that the oil drops penetrate and mix with entire air charge Atomization and diffu-
sion of the oil is brought about solely by the velocity energy of the oil spray.
      Precombustion – chamber Engines. This engine is one in which a small separated part of
the combustion chamber communicates with the main part in the cylinder, through one or more
small passages or orifices and the fuel is injected into the small ( precombustion) chamber op-
posite its point of communication with the cylinder. In an engine of this type all of the fuel in-
jected must necessarily pass through the precombustion chamber.
      Turbulence – chamber Engines. – Turbulence – chamber engines are similar in form and
arrangement of parts to the precombustion – chamber type, the main difference between them
being one of proportions, in that the separated portion of the combustion chamber and cross –
sectional area of the passage ( or passages) between the latter and the main chamber are smaller
in the precombustion – chamber engine. In a turbulence – chamber engine a section through the
chamber which cuts the communicating passage in halves is at least approximately circular in
form, whereas in a precombustion – chamber engine it is most likely to be rectangular.
      In the turbulence – chamber engine the energy necessary to accomplish a rapid and
through intermixture of the air and fuel charges is derived from two sources – the kinetic ener-
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