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A holistic modelling approach has been employed to predict combustion, cyclic variability and knock propensity of a turbocharged downsized SI engine fuelled with gasoline. A quasi-dimensional, thermodynamic combustion modelling approach has been coupled with chemical kinetics modelling of autoignition using reduced mechanisms for realistic gasoline surrogates. The quasi-dimensional approach allows a fast and appreciably accurate prediction of the effects of operating conditions on the burn-rate and makes it possible to evaluate engine performance. It has also provided an insight into the nature of the turbulent flame as the boost pressure and speed is varied. In order to assess the sensitivity of the end-gas chemical kinetics to cyclic variability, the in-cylinder turbulence and charge composition were perturbed according to a Gaussian distribution.

Gasoline engine downsizing has become a popular and effective approach to reduce CO2 emissions from passenger cars. This is typically achieved in the form of a boosted direct injection gasoline engine, which are typically equipped with variable valve timing (VVT) devices on the intake and/or exhaust valves. This paper describes the synergies between valve timings and boost based on experimental investigations in a single cylinder gasoline direct injection spark ignited (DISI) engine with variable cam phasing on both the intake and exhaust cams. Two cam profiles have been tested to realize Miller cycle and compared with the standard camshaft. One cam features a long opening duration and standard valve lift for Late Intake Valve Closing (LIVC) and the other cam has a short opening duration and low valve lift for Early Intake Valve Closing (EIVC).

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.

Particulate emissions are of growing concern due to health impacts. Many urban areas around the world currently have particulate matter levels exceeding the World Health Organisation safe limits. Gasoline engines, especially when equipped with direct injection systems, contribute to this pollution. In recognition of this fact European limits on particulate mass and number are being introduced. A number of ways to meet these new stringent limits have been under investigation. The focus of this paper is on particulate emissions reduction through improvements in fuel delivery. This investigation is part of the author's ongoing particulate research and development that includes optical engine spray and combustion visualisation, CFD method development, engine and vehicle testing with the aim to move particulate emission development upstream in the development process.

In order to optimize the 2-stroke uniflow engine performance on vehicle applications, numerical analysis has been introduced, 3D CFD model has been built for the optimization of intake charge organization. The scavenging process was investigated and the intake port design details were improved. Then the output data from 3D CFD calculation were applied to a 1D engine model to process the analysis on engine performance. The boost system optimization of the engine has been carried out also. Furthermore, a vehicle model was also set up to investigate the engine in-vehicle performance.

Highly downsized, Direct Injection (DI) engines benefit strongly from cylinder scavenging where possible, to reduce internal residuals thereby reducing the occurrence of knock. Some researchers also suggest that non-homogeneous distribution of internal residuals at high load could contribute to pre-ignition or ‘mega-knock’ with much higher pressure amplitude than that of common knock. For this reason, a computational study was conducted to assess the residual gas fraction and in-cylinder distribution, using the combustion geometry of the three cylinder, 1.2L MAHLE Downsizing engine, which has proven to be a very robust and reliable research tool into the effects of combustion effects under a number of different operating conditions. This study used a CFD model of the cylinder gas exchange. ES-ICE coupled with STAR-CD was employed for a moving mesh, transient in-cylinder simulation.

Emissions legislation, fleet CO₂ targets and customer demands are driving the requirements for reducing fuel consumption. This is being achieved in the gasoline market in the near term through the adoption of engine downsizing. In order to reduce fuel consumption further and in the wider real-world operating region complimentary technologies are being investigated and applied to an extreme downsized engine. In this paper future gasoline engine technologies are applied and experimentally assessed in terms of fuel consumption improvement whilst the impact of subsequent loadings on the thermal management system have been simulated, both over drive cycle and using real-world drive data.

Downsizing of the spark ignition engine is accepted as a key contributor to reducing fuel consumption. Turbocharged engines are becoming commonplace in passenger vehicles, replacing naturally aspirated larger capacity engines. However, turbocharged engines have typically suffered from “lag” during transient operation. This perceived effect is a combination of the low speed steady state torque and a slower rate to reach maximum torque during a load step. In order to increase customer acceptance of downsized concepts it is vital that the low speed torque and transient response are optimized. Variable Length Intake Manifolds (VLIM) have long been an established method of improving the full load performance of naturally aspirated engines. The manifold length being “tuned” to provide a high-pressure pulse at intake valve closing to maximize cylinder filling and deliver improved performance.