Factors affecting combustion in a high speed compression ignition oil engine

Jafar, D. Ul-D. (1936). Factors affecting combustion in a high speed compression ignition oil engine. University of Birmingham. Ph.D.

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Abstract

The success of the high speed Diesel engine depends greatly upon the combustion-process. Rotational movement of the air is probably the only successful means for uniform distribution of the liquid fuel inside the combustion chamber; thus successful and more or less complete combustion is achieved by bringing the air in contact with the fuel, at the right moment. Different methods have been employed to produce this rotational movement inside the combustion chamber, but up to the present there has not been published a great deal of information on the principles of its production, in so far as the poppet valve type engine is concerned. From the experiments carried out by the author, with an open type combustion chamber, one draws the conclusion that an optimum air swirl may exist with a shrouded inlet valve. The velocity of the air, through the inlet valve, was varied at first Toy altering the extent of shroud, and later on by varying the lift of the inlet valve. The jet of the air and its direction on entering the cylinder may influence the fuel consumption. Under all conditions, the rotational movement of the air resulted in a much better fuel consumption than the indiscriminate movement produced when an unshrouded inlet valve was used.

The delay period as measured by the cathode ray oscillograph high speed engine indicator and a neon tube arrangement for measuring the time of injection, seems to be variable in time and decreases, in most of the cases, as the engine speed increases.

The "Diesel knock" which may be due to the rate of pressure rise, is probably caused by the accumulation of the fuel entering the combustion chamber prior to ignition. This seems to be eliminated somewhat by the introduction of a minute quantity of the fuel before the top dead centre (Pilot Injection).

The effect of injecting Parrafin (Kerosene) and Petrols have been studied, the delay period and Torque was measured when timing of injection was varied over a big range. It is probable that the spontaneous ignition angle (S.I.A.) may bear a relation to the delay Period and Diesel knock.

The S.I.A. is defined as the critical angle between the retarded position of injection, at which the fuel ceases firing or fires, and top-dead-centre.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):