Study on knocking phenomena in a spark-ignition engine

Knocking phenomena were investigated using a specially designed spark-ignition engine which could be ignited only once. This single-event engine has a bore of 78 mm, a stroke of 85 mm and a simple disk-type combustion chamber with compression ratio of l0.4. A homogeneous mixture of n-butane, oxygen and argon, or n-butane, oxygen, argon and nitrogen was used. As a result, it was found that the ion current and OH emission vary simultaneously with the pressure oscillation due to knocking. Furthermore, it was recognized that the Livengood-Wu integral is effective for predicting the occurrence time of knocking. Several definitions of knocking intensity and the effects of engine speed, ignition timing and mixture strength on the knocking intensity were investigated.