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An air-assisted fuel vaporiser (AAFV), designed to replace the conventional fuelling system has been tested on a 3.0-litre development engine under simulated cold-Start conditions. Providing the cold engine with pre-vaporised fuel removed the need for an enriched mixture during start-up. Comparisons between the AAFV and standard fuelling systems were performed. Engine-out hydrocarbon (HC) exhaust emissions were measured during cold-start and the ensuing two minutes. Fuel spray characterisation was also conducted using a steady flow test rig designed to mimic inlet port conditions of air flow and manifold pressure over a wide range of engine operation.

Underhood simulations are proving to be crucially important in a vehicle development program, reducing test work and time-to-market. While Computational Fluid Dynamics (CFD) simulations for steady forced flows have demonstrated reliable, studies of transient natural convective flows in engine compartments under heat-soak (key-off condition with engine and turbocharger emitting high heat flux) are not yet carried out due high computing demands and lack of validated work. The present work aims to computationally characterize the thermally-driven flow in a simplified half-scaled underhood compartment and to experimentally determine the validity of the CFD approach. The commercial software VECTIS was employed for the numerical simulations. Surface temperatures of components as well as the spatial distribution of the air temperature were measured under both steady state and transient (cooling) condition.