The Effect of Combustion Chamber Shape on the Rate of Combustion in a Spark Ignition Engine

Measurements have been made of the rate of flame propagation, the cylinder pressure and the combustion rate for twenty one spark ignition engine combustion chamber designs. These show that, for a given compression ratio, the flame speed is not significantly affected by chamber design. However, the rate of combustion, the pressure history and cyclic dispersion are greatly affected.

A computer simulation has been developed which uses a simple but effective integration technique to determine the combustion chamber geometric parameters. This, too, shows that combustion chamber design has a marked effect on combustion rate and that the effect is due to the degree of compactness of the chamber.

The paper includes also work on spark plug position and dual spark plugs.