Abstract
For improving the performances of an open-chamber diesel engine, it is important before everything to improve the combustion process of the pre-mixture and the mixture formation followed immediately by the combustion.
In the present paper, it was investigated how much the flame progress, which is varied with the locality of the pre-mixture formed by auxiliary fuel, effects on the performances of engine, especially, the engine output, the exhaust smoke and the NO concentration. The results obtained may be briefly summarized as follows:
(1) If the auxiliary fuel is located at easily ignitable zone of main spray, for example, the top or the middle part of the spray, the exhaust smoke clears faintly off, but the engine output decreases. Thus, it is most favourable to distribute the auxiliary fuel at the root of main spray.
(2) The double injection method using a single injection nozzle is not effective against the improvement of engine performances. This is because the pilot fuel is placed at easily ignitable zone of the spray injected later. To make a more fruitful use of this method, the pre-mixture of pilot fuel should be more lean by injecting the fuel at an earlier stage of the compression stroke.
