Experimental Study of Diesel Engine Cycle-to-Cycle Variation—Part I: Analysis of Cycle-to-Cycle Cylinder Pressure Variation

Abstract

With the increased use of marine diesel engines, engine-induced vibration has become an important problem. The vibration is caused by engine output variation, which has not been fully documented. In this paper the results of an analysis of the cycle-to-cycle variation in the cylinder pressure of a single-cylinder diesel test engine are presented. Data covering tests with different compression ratio settings and speeds are analyzed in terms of (a) cycle-to-cycle variation in maximum cylinder pressure Pmax and (b) cycle-to-cycle variation in the combustion work, denoted PI. Special tests are made to validate the data acquisition and data reduction system. The validation shows that the cylinder pressure measurements from the test engine run as a spark-ignition engine are in good agreement with published results. Analysis of the diesel engine test measurements show that the coefficient of variation in the diesel engine cylinder pressure is smaller than the spark-ignition engine value. These results also show there is relatively little correlation between the cycle-to-cycle coefficient for variation of the maximum pressure and the corresponding variation in the combustion work, PI.