Refine Your Search

Search Results

Author:
Viewing 1 to 8 of 8
Technical Paper

Development of a Pre-Chamber Combustion System for the Magma xEV Engine

2022-03-29
2022-01-0422
The electrification of powertrains provides a critical opportunity to change the way that engines are designed and developed, allowing their efficiency to be increased and their cost reduced. This paper draws on ongoing Ricardo projects in the field of dedicated hybrid engines (DHEs). The Magma xEV combustion concept employs very high compression ratio, long stroke architecture, and advanced ignition and knock mitigation technologies, for DHEs requiring the highest efficiency. In the latest research project a pre-chamber combustion system (with both active and passive operation) has been applied to the Magma xEV engine, in order to enable the highest levels of charge dilution and further increase brake thermal efficiency. The research focussed on benefits of pre-chamber ignition as compared to conventional spark ignition and corona discharge ignition. The comparison of charge dilution using excess air (lean operation) and exhaust gas recirculation are presented.
Technical Paper

Validation of a CFD Model of a Hollow-Cone Spray with Gasoline Fuel Blends

2011-04-12
2011-01-0379
This paper presents the summary of the development of a two-phase spray model of a hollow-cone fuel injector commonly applied to spray-guided, gasoline direct injection, (SGDI) engines. The model was simulated using the Ricardo VECTIS CFD code and takes into account the physical and chemical effects of oxygenated fuel blends (flexfuels). The characteristics of the fuel sprays at typical gasoline part-load conditions, identified in a parallel study, were of particular interest. An injection duration of 0.3 ms was chosen which represented a stratified charge, unthrottled, part-load operating condition in a spray guided GDI engine with a piezoelectric fuel injector and a fuel injection pressure of 200 bar gauge. In the first instance, the spray model was validated against data recorded in a constant volume spray chamber. Secondly, the robustness of the model was tested against data measured in an optically-accessed engine.
Technical Paper

Multiple Injection Strategies for Improved Combustion Stability under Stratified Part Load Conditions in a Spray Guided Gasoline Direct Injection (SGDI) Engine

2011-04-12
2011-01-1228
Compared to conventional homogeneous direct injection or port-fuel injected engines, the second generation, spray guided, direct injection engine (SGDI) has the potential for significantly improved fuel economy during part load stratified charge operation. Multiple fuel injection strategies can be utilised to increase the unthrottled operating range, leading to further improvements in fuel economy. However, careful optimisation of these strategies is essential to ensure that benefits are maintained whilst further minimising emissions within combustion stability limits and consumer driveability demands. The effects of multiple injection strategies upon fuel consumption, emissions and combustion stability were investigated in a single cylinder Ricardo Hydra engine with a spray guided combustion system. An outwardly opening piezoelectric actuated injector was employed. The fuel injection strategy utilised up to five injections per engine cycle.
Technical Paper

An Innovative Control System for a 2/4 Stroke Switchable Engine

2007-04-16
2007-01-1199
The 2/4SIGHT engine concept is based on a novel design of combustion system, which makes use of an electric-hydraulic valvetrain and advanced control technologies, enabling automatically controlled dynamic switching of the engine between two- and four-stroke operations. This concept has the potential to improve fuel consumption by up to 30% compared to a conventional gasoline engine. A 3 cylinder GDI engine with two stage boosting system and electro-hydraulic valvetrain is the main application for this project, with 6 cylinder application being studied in simulation. The design of a Control System poses several challenges due to the simultaneous introduction of several innovations such as advanced boost system, electro-hydraulic valvetrain system and two/four stroke operating mode. In order to develop and optimise the design of the control system, an integrated simulation environment has been developed.
Technical Paper

Turbocharging Concepts for Downsized DI Gasoline Engines

2004-03-08
2004-01-0036
Reducing engine swept volume (so-called ‘downsizing’) offers the potential to meet future tighter CAFÉ standards and reduced CO2 vehicle emissions in Europe. In downsizing the gasoline engine, a key challenge is controlling octane requirement without sacrificing fuel economy. The authors have investigated five alternative approaches on a turbocharged DI gasoline engine: Conventional stoichiometric operation, with reduced compression ratio (CR) Lean Boost DI (LBDI) with lean operation at full-load to control octane requirement while maintaining a high CR EGR Boost with cooled EGR dilution rather than excess air to control octane requirement Miller cycle concept, where valve-timing strategies are employed to reduce the effective compression ratio at high load Dual injection strategies to control octane requirement Each approach has been investigated using engine performance and vehicle simulation codes.
Technical Paper

Air-Fuel Mixing in a Homogeneous Charge DI Gasoline Engine

2001-03-05
2001-01-0968
For optimum efficiency, the direct injection (DI) gasoline engine requires two operating modes to cover the full load/speed map. For lower loads and speeds, stratified charge operation can be used, while homogeneous charge is required for high loads and speeds. This paper has focused its attention on the latter of these modes, where the performance is highly dependent on the quality of the fuel spray, evaporation and the air-fuel mixture preparation. Results of quantitative and qualitative Laser Induced Fluorescence (LIF) measurements are presented, together with shadow-graph spray imaging, made within an optically accessed DI gasoline engine. These are compared with previously acquired air flow measurements, at various injection timings, and with engine performance and emissions data obtained in a fired single cylinder non-optical engine, having an identical cylinder head and piston crown geometry.
Technical Paper

Application of Optical Techniques to the Study of Mixture Preparation in Direct Injection Gasoline Engines and Validation of a CFD Model

2000-03-06
2000-01-0538
The performance of a direct injection gasoline engine (G-DI) is highly dependent on the quality of the air-fuel mixture preparation. This is of particular importance when operating at a stratified charge condition, where the ideal mixture distribution would be a stoichiometric region around the spark plug, surrounded by air. To achieve this ideal situation over a wide range of speeds and loads is extremely difficult, requiring an understanding of the fuel spray, the in-cylinder air motion and their interactions. This paper presents the results of Phase Doppler Anemometry (PDA) and Laser Induced Fluorescence (LIF) measurements made both within an optically accessed direct injection gasoline engine and under atmospheric conditions. The experimental results are compared with those of a VECTIS Computational Fluid Dynamics (CFD) simulation of the same engine.
Technical Paper

Gasoline Combustion Chambers-Compact or Open?

1983-11-07
830866
A single cylinder research engine has been used to study a range of gasoline combustion chamber designs which have been divided into three categories open, compact and four valve. Measurements of fuel consumption and exhaust emissions are presented at full load and part load conditions, and a comparison is made of the best chamber from each category. At full load the performances of the three chambers were very similar at low speeds but at high speeds the superiority of the four-valve was clearly shown. At part load there were significant differences in the burn rate when operating at lean mixtures with the compact design showing the highest level and hence the most extended lean limit. The relationship between part load fuel consumption and full load octane requirement is presented as a method of comparing the relative performance of a range of combustion chamber designs.
X