Combustion Characteristics and Cycle-By-Cycle Variation in a Turbocharged-Intercooled Gasoline Direct-Injected Engine

This work experimentally investigated the combustion characteristics and cycle-by-cycle variations of a turbocharged, intercooled, gasoline direct injected spark ignition (DISI) engine at a wide range of operating conditions. The cycle-by-cycle variations have been characterized by the coefficient of variance of (COV) cylinder pressure against crank angle, the indicated mean effective pressure (IMEP) and 50% mass fraction burned. The combustion characteristics and cyclic variability of the DISI engine are compared with data from throttle body injected engines throughout the analysis to draw conclusions. The present work identified that the COV of pressure reaches a minimum value at the end of the compression stroke and this minimum value is independent of engine type and the loading conditions investigated. It also identified that the maximum COV value of the pressure against crank angle during combustion does not change significantly with load for the throttle body injected engine. However, the changes are significant for DISI engine.