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Video imaging has been used to investigate the evolution of liquid fuel films on combustion chamber walls during a simulated cold start of a port fuel-injected engine. The experiments were performed in a single-cylinder research engine with a production, four-valve head and a window in the piston crown. Flood-illuminated laser-induced fluorescence was used to observe the fuel films directly, and color video recording of visible emission from pool fires due to burning fuel films was used as an indirect measure of film location. The imaging techniques were applied to a comparative study of open and closed valve injection, for coolant temperatures of 20, 40 and 60 °C. In general, for all cases it is shown that fuel films form in the vicinity of the intake valve seats.

Video imaging has been used to investigate the evolution of liquid fuel films on combustion chamber walls during a simulated cold start of a port fuel-injected engine. The experiments were performed in a single-cylinder research engine with a production, four-valve head and a window in the piston crown. Flood-illuminated laser-induced fluorescence was used to observe the fuel films directly, and color video recording of visible emission from pool fires due to burning fuel films was used as an indirect measure of film location. The imaging techniques were applied to a comparative study of single and dual spray fuel injectors for both open and closed valve injection, for coolant temperatures of 20, 40 and 60°C. In general, for all cases it is shown that fuel films form in the vicinity of the intake valve seats.

In this work, we describe an optical diagnostic based on infrared-absorption spectroscopy that can be applied to production-like engines to evaluate the cylinder-to-cylinder EGR distribution. We have applied this diagnostic to a small-bore Diesel engine and performed measurements under both steady-state and transient conditions. The IR absorption diagnostic is shown to have a very low detection limit along with high precision, and produces highly credible results. Both crankangle-and cycle-resolved data were acquired in order to demonstrate the temporal measurement of the EGR concentration during the intake stroke, and during a sequence of cycles that define an engine transient. The results confirm the capabilities of the diagnostic, and in addition, illustrate interesting insight regarding the cylinder-to-cylinder EGR distribution.