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The transient behaviour of the fuel spray from an air assisted fuel injector has been investigated both numerically and experimentally in a Constant Volume Chamber (CVC) and an optical engine. This two phase injector is difficult to analyse numerically and experimentally because of the strong coupling between the gas and liquid phases. The gas driven atomization of liquid fuel involves liquid film formation, separation and break up and also liquid droplet coalescence, break up, splashing, bouncing, evaporation and collision. Furthermore, the liquid phase is the dominant phase in many regions within the injector. Experimental results are obtained by using Mie scattering, Laser Induced Fluorescence (LIF) and Laser Sheet Drop sizing (LSD) techniques. Computational results are obtained by using a mixed Lagrangian/Eulerian approach in a commercial Computational Fluid Dynamic (CFD) code.

Air-fuel ratio control in gasoline engines has so far relied upon the fact that the stoichiometric air-fuel ratio of gasoline is an identified constant, largely thanks to its consistent chemical composition. In the case of Liquefied Petroleum Gas (LPG), chemical composition is subject to high variability due to geological and economic factors, amongst others. The implication of this variability is unpredictable stoichiometric air-fuel ratio of the fuel supply within any given vehicle, and ultimately degraded control of air-fuel ratio. This paper addresses the problem of stoichiometric air-fuel ratio estimation by evaluating the measurement and modeling of the relative permittivity of fuel, and also the method of iterative computation. For the estimation method proposed in this paper, simulation results are presented to demonstrate its effectiveness.

A survey of the on-road petrol consumption of Australian passenger cars provided data which has been analysed for effects on fuel consumption caused by features such as transmission type, vehicle inertia class, engine size, air conditioning presence and vehicle location. Results show that cars with automatic transmissions consistently have higher petrol consumption than manuals for all inertia classes - 15% higher in city conditions and 11% higher in highway conditions. There is also a penalty for automatic transmissions at most engine sizes, although the penalty is relatively larger for smaller engine capacities. Presence of air conditioning was found to increase petrol consumption by 13.5% on average, but the data did not allow the impact of frequency of use to be determined. Coastal driving conditions resulted in petrol consumption being 9.4% higher than for inland conditions, and cars driven in winter had 4.4% greater fuel consumption than cars driven in summer.

A phenomenological model having modular formulation is presented for combustion in the open chamber diesel engine. The modules for fuel injection, jet penetration and droplet formation have been calibrated outside the engine in a high pressure, fixed volume chamber by high speed photographic and laser analysis of single spray ‘shots’. In the diagnostic mode of operation the chemical components of the combustion reaction are estimated. In the predictive mode of operation the model is used to estimate engines’ pressure diagrams and various other combustion characteristics of the fuels over a wide range of speed and load conditions. Finally, sensitivity analyses of the reaction rate constants of five fuels namely distillate, sunflower oil, rapeseed oil and methyl esters of sunflower and rapeseed oils, to some of the model inputs are presented.