Analysis of Local Pressures, Surface Temperatures and Engine Damages under Knock Conditions

Abstract

The mechanism of surface damage in the combustion chamber of SI-engines is still unknown. More agreement is found in the literature about the theory of knock as an uncontrolled autoignited combustion with high flame velocities followed by pressure oscillations. Although there are many investigations dealing with engine damage, there is still a lack of detailed local information of pressure and temperature histories in the damage zones of the combustion chamber. In this work four pressure transducers and nine film thermocouples were inserted in a single cylinder engine with Heron type production combustion chamber and high compression ratio. The data obtained from cylinder pressure and combustion chamber surface temperature traces were registered synchronously with the Volkswagen high-speed data acquisition system HDS and analyzed with an on-line computer. Surface damage development was studied on a four cylinder production engine under conditions similar to those of the single cylinder engine measurements. Furthermore ideas how to avoid these damages are discussed.