An Analysis of Combustion Knock in a Diesel Engine

The present work theorizes the phenomenon of rapid combustion in a diesel engine by introducing a concept that the ignition delay of the injected fuel element varies from time to time according to the changes in temperature and pressure of the charge. In this process the rate of heat release is multiplied by the rate of shortening of the ignition delay, thus causing an explosive combustion. In this paper, a theoretical analysis was conducted to establish the course of the changing delay and thereby the physical and chemical features of the process were described by simultaneous differential equations. Discussions were made on the influences of the following factors on the maximum rate of heat release ; namely, ignition delay, injection rate, pilot injection and vaporization velocity of fuel. The results show that the present theory can successfully describe the qualitative nature of the combustion knock in a diesel engine.