Optical Investigations in Stratified Gasoline Combustion Systems with Central Injector Position Leading to Optimized Spark Locations for Different Injector Designs

In the present work the integral laser induced exciplex fluorescence (LIEF) measurement technique is used in a transparent engine to define the location of the spray where a maximum vapor occurrence probability is combined with the minimum of liquid fuel occurrence probability. This location, determined with additional boundary conditions, e.g. the temporal occurrence of the defined ignition condition relative to the end of injection, is presented for three different injector types, a swirl, a multi-hole and an outward opening injector. Finally, all spark locations are tested with all injectors throughout 250 combustion cycles in the transparent engine in order to prove if the initial criteria is suitable.