Study of burning rate and nature of combustion in diesel engines

Abstract

In the present investigation the burning rates in diesel engines have been studied in some detail and the rate-controlling factors examined. Chemical kinetics based on activated collision could not play a part because otherwise the whole process would be very temperature sensitive, and this is not consistent with results from experimental investigation. The temperature drop during the expansion stroke would demand a drop in burning rate far greater than is shown by experiment, while the proportional increase in burning rate with engine speed could not be accounted for by the small increase in cycle temperature. Indeed the major factors affecting the burning rate are injection rate, engine speed, and combustion chamber design, all of which directly affect mixing. For a D.I. engine with central multihole nozzle, it is found that a relationship exists between the rate of injection and rate of burning. This relationship is independent of operating condition and therefore can be used to predict the rate of burning, and hence the cylinder pressure diagram from the rate of injection diagram.