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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 advantages of closed, loop over open loop control systems are generally recognised. However, existing engine management systems implement most control functions in open loop because suitable feedback sensors are not available. Even for so-called closed loop air fuel ratio controllers, shortcomings of the exhaust gas oxygen (EGO) sensor limit the potential effectiveness of closed loop control. A more direct measure of the combustion process, such as cylinder pressure, can yield sufficient information for the closed loop operation of many of the combustion control functions; this paper presents the results of a prediction algorithm which can derive a variety of feedback signals from cylinder pressure. Cylinder pressure, together with several combustion variables, including air-fuel ratio, exhaust gas recirculation rate, and NOx HC, CO and CO2 emissions were measured at various operating points.

A compact passenger car was modified to allow operation with up to six manual gear ratios and up to 35.4 mile/h per 1000 rev/min. Fuel consumption tests were carried out at steady state conditions, over the U.S. Federal urban drive cycle and on the road. Fuel economy improvements of up to 24% were achieved on the road, and up to 25% on the chassis dynamometer over the urban cycle, confirming computer predictions.

The use of high ratio compact combustion chambers in gasoline engines has been investigated. The objectives of the research are improved fuel economy within a given set of exhaust emission constraints. The effects of a number of parameters such as swirl, compression ratio and combustion chamber geometry have been investigated, and the conclusions are that for Europe, 13:1 compression ratio is feasible and should yield 10% better fuel economy in passenger cars, while for the USA and Japan, 11:1 compression ratio is preferable, and should yield about 5% better fuel economy.

A research programme has been carried out to investigate the effects of operating gasoline engines with different combustion systems. The results showed that at high compression ratios (13:1) compact combustion chambers allowed an increase in compression ratio of between 1 and 2½ numbers for a given fuel quality compared to conventional designs. Fuel economy benefits of about 10% could be achieved by using high ratio compact chambers and lean operation.

This paper describes latest results from the Ricardo heavy duty diesel engine research programme. Using a Diesel Kiki P-TICS II injection system, matched to a low swirl combustion chamber, emission results well within the US 1991 engineering targets have been achieved with good fuel economy. Very low NOx levels have also been demonstrated whilst maintaining good fuel economy and particulate emissions within the 1991 standards. Analysis of results indicates that injection timing and rate control, as embodied in the P-TICS approach, is a key technology for achieving these low emissions with good fuel economy.

The spatial variation of instantaneous heat transfer in a highly rated DI diesel engine (130 mm bore, 150 mm stroke) has been investigated. Measurements have been made at key locations within the combustion chamber (valve bridge, above the piston bowl lip and bore edge) at test conditions covering the engine speed and load range. Total and radiative heat flux probes have been designed and developed to enable both the convective and radiative heat transfer components to be quantified. Transient calibration techniques have also been developed to establish the dynamic characteristics of the heat flux probes. This has removed the uncertainty normally associated with surface thermocouple diffusivity values. Considerable spatial variations in both peak and mean heat transfer have been found. The measured spatial and temporal variation in heat flux have been compared with established heat transfer models.

Natural gas is one of the alternative fuels to diesel being considered for low emissions heavy-duty applications. The favoured operating strategies for low emissions SI gas engines are identified as those with high levels of dilution - stoichiometric operation with EGR, and lean-burn. A well-matched exhaust catalyst is needed to produce the lowest emissions levels. Increasing the accuracy of transient air-fuel ratio control is shown to improve the emissions still further. The most favourable combinations of engine operating strategy and control accuracy are identified with respect to fuel economy and first cost. The Co-Nordic Natural Gas Bus Project is an example of an engine development programme aimed at achieving the lowest possible exhaust emissions levels, and as such uses the lowest emissions approach of a stoichiometric engine strategy with EGR and high accuracy control.

Ricardo have developed a systematic approach for the design of transient engine control strategies using advanced control techniques. The methodology was initially applied to the design of a testbed speed and torque controller. This enabled complex transient tests to be carried out with equipment normally used for steady-state testing. The same techniques were applied to the design of a controller for a variable geometry turbocharger aimed at vehicle applications. The influence of different control strategies on emissions and fuel economy was evaluated on a heavy-duty diesel engine over a section of the US FTP cycle. Particulate reductions of up to 34% were achieved without increasing NOx.

The market share of Gasoline Direct Injection (GDI) vehicles has been increasing, promoted by its positive contribution to the overall fleet fuel economy improvement. It has however been reported that this type of engine is emitting more ultrafine particles than the Euro 6c Particle Number (PN) limit of 6·1011 particles/km that will be introduced in Europe as of September 2017 in parallel with the Real Driving Emission (RDE) procedure. The emissions performance of a Euro 6b GDI passenger car was measured, first in the OEM build without a Gasoline Particulate Filter (GPF) and then as a demonstrator with a coated GPF in the underfloor position. Regulated emissions were measured on the European regulatory test cycles NEDC and WLTC and in real-world conditions with Portable Emissions Measurement Systems (PEMS) according to the published European RDE procedure (Commission Regulation (EU) 2016/427 and 2016/646).

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.

With current technology, a PEM fuel cell powered vehicle requires a plentiful supply of clean hydrogen to achieve good performance. This can be made available via an on-board methanol reformer. Before the reformer reaches operating temperature it is necessary to obtain energy from an alternative source, such as a battery, in order to power the vehicle. This paper introduces a dynamic model of a methanol reformer fuel cell powered vehicle. The vehicle model is driven over the FTP drive cycle, from a cold start, using various warm up strategies. In this way, different strategies are evaluated in terms of performance and fuel efficiency.