Combustion and Emissions Characteristics of Orbital's Combustion Process Applied to Multi-Cylinder Automotive Direct Injected 4-Stroke Engines

Houston, Rodney; Cathcart, Geoffrey

doi:10.4271/980153

Cited by 52 publications

(11 citation statements)

References 8 publications

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“…Too little air will not provide sufficient flow for atomizing the fuel. In general systems are operated such that the injected air/fuel mass ratio is 0.2 or above [10]. Figure 15 is a plot of the A/F injected mass ratio as a function of mixing cavity volume.…”

Section: Figure 14mentioning

confidence: 99%

Design of a Compression Pressurized Air Blast Direct Injection System for Small Displacement Two-Stroke Engines

Gitano-Briggs

Kirkpatrick

Wilson

2003

Design and Control of Diesel and Natural Gas Engines for Industrial and Rail Transportation Applications

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In two-stroke engines replacement of carburetors with direct fuel injection systems greatly reduces engine emissions and fuel consumption by eliminating fuel short-circuiting. Air-blast direct fuel injection using a dedicated air pump has been successfully applied to both two- and four-stroke engines. In this study we re-examine the design of a low cost compression pressurized direct injection system. This system uses gases extracted from the combustion chamber during the compression stroke to supply pressure for the air blast injection, thus eliminating the air pump [1,2]. Gases, predominantly scavenging air, are transferred to a mixing cavity from the combustion chamber via a small (5mm diameter) solenoid poppet valve as the piston rises during the compression stroke. Proper functioning of the system requires careful optimization of the mixing cavity size and the blast valve timing to ensure adequate mixing cavity pressure and fuel atomization. To assist in the optimization of these design parameters a one-dimensional fluid dynamics model has been developed. Parameter sensitivity studies were carried out using the model to determine the optimum cavity size, blast valve timing, and fuel injection duration. These parameters were optimized over a wide range of engine speeds and throttle settings. Results show that a mixing cavity pressure of 500 kPa is attainable over the range of 1000 to 6000 rpm, from closed throttle to wide open throttle (WOT) without cavity pressurization encroaching into the ignition regime. Fuel maps and valve timings are presented and results are contrasted with the carbureted case, showing improved fuel efficiency and emissions for the direct injection system. These data will be used in the design of a physical demonstration engine.

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Section: Figure 14mentioning

confidence: 99%

Design of a Compression Pressurized Air Blast Direct Injection System for Small Displacement Two-Stroke Engines

Gitano-Briggs

Kirkpatrick

Wilson

2003

Design and Control of Diesel and Natural Gas Engines for Industrial and Rail Transportation Applications

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“…The main driver for this change is the reduced fuel consumption available (typically 10 -20% better than an otherwise-equivalent PI 4-stroke engine), in conjunction with low engine-out NOx [11] [12] . In light of this development, a logical question is: "Why not apply DI to small vehicle 4-stroke engines also ?"…”

Section: Overview -2-stroke Vs 4-stroke Systemsmentioning

confidence: 99%

Advanced Electronic Fuel Injection Systems - An Emissions Solution for Both 2 - and 4 - Stroke Small Vehicle Engines

Archer¹,

Bell²

2001

SAE Technical Paper Series

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This paper describes two advanced electronic fuel injection systems for small vehicles which have recently become commercially available. Both systems have been designed and developed by the authors' organisation.One of the two systems ('aSDI') has been designed and developed for 2-stroke engines and the other ('SePI') for 4-stroke engines. Both systems are intended for application on small vehicles fitted with small 1 -2 cylinder gasoline engines of displacement 50 -250 cm Fuel consumption and emissions results from both systems are presented, and in both cases it is shown that engine-out exhaust emissions meet current and future limits in Europe, India and Taiwan, without the need for exhaust after-treatment. It is also shown that both systems offer significant fuel savings relative to otherwise-equivalent, carburetted baseline vehicles.Other important benefits of these systems which are discussed in this paper are improved cold start and improved driveability.The paper also includes a short overview of the performance and cost implications of both systems relative to alternative emissions control methods.1 For reasons of convenience, these types of vehicles will be referred to collectively as 'small vehicles' in this paper.

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“…Other manufacturers have developed swirl systems with involute or other various piston bowl shapes [18, 23, 32]. Air-assist injectors have also been advocated by Orbital and others [14,25], as the added mixing with air allows this type of direct injection to be retro-fitted to existing PFI engine designs. It has been hypothesized that the difference of these many approaches indicates a lack of complete understanding of the physics involved.…”

Section: Introductionmentioning

confidence: 99%

Piston Fuel Film Observations in an Optical Access GDI Engine

Karlsson¹,

Heywood²

2001

SAE Technical Paper Series

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Increasing pressure for reduced fuel consumption, particularly in Japan and Europe, has motivated the development of various engine concepts that improve part-load efficiency. One of these concepts is Gasoline Direct Injection, or GDI. By injecting fuel under high pressure directly into the combustion chamber later in the engine cycle and using various piston geometry and combustion chamber airflow techniques, a locally stratified, globally lean mixture can be used to obtain part load power with greater efficiency. Emissions concerns, however, particularly hydrocarbons from unburned mixture and liquid films on the piston and cylinder walls, are a major concern.The purpose of this project was to observe the interaction of a GDI fuel spray with the moving piston crown in an optical access engine, describe the interaction qualitatively, devise a means to measure the residual fuel film on the piston quantitatively, and compare the results with a Computational Fluid Dynamics (CFD) simulation. CFD was also used extensively to aid in the design of the experimental apparatus, particularly in selecting the spray and injection parameters that would allow stratified charge operation in the simple geometry available in the optical engine.The CFD simulations predicted that within the operating window for stratified charge operation, between 1% and 4% of the injected fuel would remain on the piston as a liquid film. The most influential parameter for the quantity of residual fuel film was the piston temperature. The experimental results support the CFD simulations qualitatively, but the amount of fuel film remaining on the piston is under-predicted. High-speed video footage shows a vigorous spray impingement on the piston crown resulting in vapor production. The primary GDI combustion process, a roughly premixed flame, is followed by a turbulent diffusion flame or "pool fire" in the region of the liquid film once the piston is warm enough to produce vapor at a high enough rate. Thanks also go to my family, for creating and shaping me as I am, the people who helped me get into MIT including

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Combustion and Emissions Characteristics of Orbital's Combustion Process Applied to Multi-Cylinder Automotive Direct Injected 4-Stroke Engines

Cited by 52 publications

References 8 publications

Design of a Compression Pressurized Air Blast Direct Injection System for Small Displacement Two-Stroke Engines

Design of a Compression Pressurized Air Blast Direct Injection System for Small Displacement Two-Stroke Engines

Advanced Electronic Fuel Injection Systems - An Emissions Solution for Both 2 - and 4 - Stroke Small Vehicle Engines

Piston Fuel Film Observations in an Optical Access GDI Engine

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