Optical studies of spray development in a quiescent chamber and in a direct-injection spark-ignition engine

摘要

The effects of fuel type and in-cylinder flow on spray formation from a multi-hole injector were studied by high-speed imaging techniques in a quiescent injection chamber and in a single-cylinder Direct-Injection Spark-Ignition (DISI) engine. To examine the effect of fuel volatility on spray formation, the injector was heated from 20°C to 120°C in the chamber for iso-octane and gasoline. The injection chamber was operated at 0.5 and 1.0 bar to mimic in-cylinder pressures for early injection strategies. Droplet sizing was also employed in the chamber using Phase Doppler Anemometry (PDA). Fuel-type and temperature effects were studied in-cylinder by operating the engine at 20°C and 90°C head temperature at 1500 RPM. For both sets of experiments, the study was carried out for two orthogonal views, relating to the tumble and swirl planes of in-cylinder flow motion. Spray formation was observed to be different for the two fuels, especially at high injector temperatures. Wetted footprint spray areas were calculated for both experimental setups.