Study on in-cylinder flow during combustion in a spark ignition engine

The measurement and study of the air flow in cylinder are usually made under motored condition and rarely under firing condition. The in-cylinder air motion and its interaction with combustion were studied under both motored and firing conditions by LDA laser Doppler anemometry in a single-cylinder 4-valve spark ignition engine. The results show that during intake, compression, expansion and exhaust processes, the mean velocity of air flow in cylinder under firing condition is quite different from that under motored condition. The higher the combustion velocity is, the greater the variation of mean velocity of air flow will be.