In-cylinder PIV measurements have been made during the latter half of the intake stroke on a plane between the inlet valves for a single cylinder optical engine operating at engine speeds of 750, 2000 and 3500 rpm. Mean vector fields for an area of 42 mm by 34 mm have been produced with vectors at approximately 1 mm resolution. The vector fields show the development of the flow field in 1.6°, 2.4° and 3.2° steps for the three respective engine speeds.Tumble ratios have been calculated from these vector fields which show that a change in the flow regime occurs between 2000 and 3500 rpm. This is caused by one of rotating vortices becoming detached from the descending piston at the highest engine speed.

This work was concerned with evaluation of the performance and emissions of potential future biofuels during advanced spark ignition engine operation. The fuels prepared included three variants of gasoline, three gasoline-ethanol blends and a gasoline-butanol fuel altogether covering a range of oxygen mass concentrations and octane numbers to identify key influencing parameters. The combustion of the fuels was evaluated in a turbocharged multi-cylinder direct fuel injection research engine equipped with a standard three-way catalyst and an external EGR circuit that allowed use of either cooled or non-cooled EGR. The engine operating effects studied at both part and boosted high load conditions included fuel injection timing and pressure, excess air tolerance, EGR tolerance and spark retard limits. A number of blends were also mapped at suitable sites across the European drive cycle under downsized engine conditions. Relative in-vehicle fuel economies were then determined via drive cycle simulation and compared to a naturally aspirated gasoline PFI engine.

No abstract

No abstract

No abstract