One of the latest advancements in injector technology is laser drilling of the nozzle holes. In this context, the spray formation and atomisation characteristics of gasoline, ethanol and 1-butanol were investigated for a 7-hole spark eroded (SE) injector and its 'direct replacement' Laser-drilled (LD) injector using optical techniques. In the first step of the optical investigation, high-speed spray imaging was performed in a quiescent injection chamber with global illumination using diffused Laser light. The images were statistically analyzed to obtain spray penetration, spray tip velocity and spray 'cone' angles. Furthermore, droplet sizing was undertaken using Phase Doppler Anemometry (PDA). A single spray plume was isolated for this analysis and measurements were obtained across the plume at a fixed distance from the nozzle exit. The droplet measurements were grouped into bins and maps were created showing droplet sizes and velocities against time and position during and post injection. All tests were performed at 120 bar fuel pressure, two injection chamber 'back' pressures (0.5 bar and 1 bar) and two injector temperatures (20 °C and 80 °C), to examine effects relevant to typical engine operating conditions with early intake stroke injection strategies, including fuel flash boiling.

Engine dowsizing is one of the most effective means to achieve the reduction in fuel consumption and CO2 emissions from passenger cars. All engine downsizing so far has been achieved through the replacement of a NA 4stroke engine with another 4-stroke boosted engine. In order to achieve further engine downsizing and downspeeding, the 2-stroke uniflow direct injection gasoline engine was studied as a potential candidate for future vehicle applications. In order to optimize the 2stroke uniflow engine performance, systematic studies were performed on the intake port design, engine geometry, and scavenging events by means of combined 3-D CFD flow analysis and 1-D engine simulation programme. This is followed by the investigation on the boost system optimization and the engine configuration for a typical passenger car. The results show that a 0.6litre 2-cylinder 2-stroke uniflow engine can be used to replace a modern 1.6litre 4-cylinder NA gasoline engine in a typical passenger car vehicle with potential improvement in performance, drivability and fuel economy.

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Introduction of novel fuels such as mixtures of ethanol or butanol with hydrocarbons, requires new fundamental