Relationship of Flame Front Pattern to Pressure and High-Speed Knock on Commercial Engines

The combustion chamber of a typical commercial engine was equipped with pressure and ionization gap transducers to determine the pressure and flame front pattern. The signals from the transducers were displayed on an oscilloscope screen and recorded by means of moving pictures shot with a speed-adjustable camera. The necessary data were obtained by measuring the parameters on the single frames which show the combustion cycles, and they were subsequently processed.

The results refer to correlations between pressure values and flame front pattern, considerations on flame front behavior and origin of knock phenomenon, and the existence of statistically different behavior between knocking and nonknocking combustion cycles.