Search Results

Conventional instrumentation, a laser doppler velocimeter and a constant temperature hot wire anemometer were used to characterise the air flow produced by a number of inlet ports typical of those used in open chamber diesel engines. In particular, directed and helical ports were included. The same ports were fitted to a motored single cylinder engine and the air motion characteristics were mapped over the speed range of the engine within the bowl and within the cylinder throughout the engine operating cycle. A comparison of the measured results from the motored engine tests and predictions based upon the steady flow results using conventional instrumentation was made. Performance tests with a single cylinder engine fitted with the same ports were carried out to determine whether or not the induction system influenced the performance of the engine in the way it generated bulk swirl or by any other property of air motion.

The application of statistical analysis methods and simulation techniques through the concept stages of a truck engine development process, in order to assist with decision making, is reported in this paper. Aspects of single cylinder engine, combustion system development and the subsequent use of modelling and simulation, to predict multi-cylinder engine behaviour, is described. Finally, the inclusion of vehicle commercial and operational information is shown to provide insights into the likely mix of technical strategies for future truck engines in the UK vehicle parc. It is seen that, in the near future especially in Europe, the likely solution for truck engines will be a mix of EGR and SCR techniques both of which will include the use of particulate filtration. However, the extent of the commercially viable application of this strategy is very dependent upon likely future market prices for the various aftertreatment and fuel technologies.

This paper describes an experimental investigation to explore and optimise the performance, economy and emissions of a direct injection gasoline engine. Building on previous experimental direct injection investigations at Ricardo, a single cylinder engine has been designed to accommodate common rail electronically controlled fuel injection equipment together with appropriate port configuration and combustion chamber geometry. Experimental data is presented on the effects of chamber geometry, charge motion and fuel injection characteristics on octane requirement, lean limit, fuel consumption and exhaust emissions at typical automotive engine operating conditions. The configuration is shown to achieve stable combustion at air/fuel ratios in excess of 50:1 enabling unthrottled operation over a wide operating range. Strategies are demonstrated to control engine out emissions to levels approaching conventional port injected gasoline engines.

Twenty-three hydrocarbon components were analysed in the exhaust emissions from a 2.3 litre gasoline engine. The effect of a three-way catalyst on emission rates was investigated, as was the effect of addition to fuel of specific aromatic and olefinic compounds. The addition of 1-hexene and 1-octene (olefins) caused statistically significant increases in reactive olefins - ethene and propene - in the exhaust. The addition of benzene and toluene led to increases in these compounds in the exhaust, and indicated that whilst fuel-toluene is the main source of toluene emissions, the emission of benzene has sources in addition to fuel-benzene. A three-way catalyst, when operating at > 600°C, eliminated most hydrocarbons except methane and traces of the light aromatics. At idle, however, the catalyst exhibited substantial selectivity towards different hydrocarbons according to their ease-of-oxidation.

It has been shown by calculation that, for given engine operating conditions, there should be an optimum rate of combustion for minimum Nox emissions from spark ignited engines. This paper gives experimental results from a single cylinder engine which confirm the theory, and show that, for a particular engine, the normal combustion rate needed reducing at zero EGR and increasing at high EGR rates, in opposition to its natural tendency to decrease. The effect on economy was a small loss at zero EGR, but an appreciable improvement at high EGR. Cyclic variation and octane requirement studies are also included.