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Previous measurements of the velocity, size and number density of droplets have been reported in one cylinder of a production two-valve engine as a function of position, crank angle, injection timing, rotational speed, load and cooling water temperature. In this paper, similar measurements are reported in two cylinders of the same engine, this time with four cylinders firing, and with two manifolds and injectors. They were obtained with a phase-Doppler velocimeter with measurements ensembled in relation to an optical shaft encoder. The engine was also instrumented to provide air and fuel flow rates and temperatures. The results show that most of the droplets emerge in a comparatively small region of the inlet valve and that the characteristics of the spray are important mainly when injection takes place with the inlet valve open.

Experiments have been performed in one cylinder of a production two-valve engine under firing conditions and quantify the velocity, size and number density of droplets as a function of position, crank angle, injection timing, rotational speed, load and cooling water temperature. They were obtained with a phase-Doppler velocimeter with measurements ensembled in relation to an optical shaft encoder. The engine was also instrumented to provide pressure traces, air and fuel flow rates and temperatures. The injection timings included those with open and closed inlet valve. The results show that most of the droplets emerge in a comparatively small region of the inlet valve and that the characteristics of the spray are important mainly when injection takes place with the inlet valve open.

Fuel intake, start and propagation of combustion were studied in a Z-liter in-line four-cylinder SI engine. Two-dimensional laser induced fluorescence was used to characterize the performance of the engine. A tunable excimer laser at 248 nm and a broadband excimer laser at 308 nm were used to measure simultaneously distributions of hydroxyl radicals and fuel. LIF measurements of fuel (iso-octane) were performed by adding diethyl-ketone as fluorescence tracer to the iso-octane. The complementary information obtained from fuel and hydroxyl radical distributions is shown and differences are pointed out. Cycle to cycle variations and averaged results are discussed as function of equivalence ratio.