Mixture Preparation and Combustion Variability in a Spray-Guided DISI Engine
File(s)SAE Paper 2007-01-4033.pdf (3.67 MB)
Accepted version
Author(s)
Aleiferis, PG
Serras-Pereira, J
Richardson, D
Wallace, S
Type
Journal Article
Abstract
In an attempt to study the numerous contributors towards cyclic variations in combustion in a direct injection spark ignition engine, simultaneous high-speed imaging of fuel injection and flame growth are undertaken on a crank-angle resolved basis in a single-cylinder optical research engine. Batches of images from 100 consecutive cycles are acquired for all conditions with synchronised in-cylinder pressure logging. The engine is motored and fired at stoichiometric conditions at 1500 RPM under part-load and wide-open-throttle conditions (0.5-1.0 bar intake pressure), with injection timing set early in the intake stroke to promote homogeneous mixture formation with a centrally mounted multi-hole injector. Liquid impingement is observed on the cylinder walls and on the piston crown with early intake injection and multiple injection strategies are employed in an attempt to reduce impingement and alter mixture preparation and subsequent combustion. The effects are investigated for iso-octane and pump-grade gasoline at engine coolant temperatures of 50 and 90 °C. Gasoline sprays showed severe deformation and partial collapse of the individual spray plumes at 90 °C, leading to a different mixture formation process relative to iso-octane, which showed no such effects at this engine temperature. Using multiple fuel injections per cycle, but maintaining the same overall air-to-fuel ratio with single-injection strategies, a significant reduction in direct impingement on the walls was observed, together with different flame growth relative to single injection. These results suggest that injection strategy and type of fuel is playing an important role in the mixture preparation process, even for homogeneous early direct injection, and that different types of multiple-injection strategies alone have the potential to modify significantly in-cylinder phenomena, affect combustion and potentially exhaust emissions. Copyright © 2007 SAE International.
Date Issued
2007-10-29
Date Acceptance
2007-07-01
Citation
SAE Technical Paper Series, 2007, 116 (3), pp.1332-1356
ISSN
0148-7191
Publisher
Society of Automotive Engineers
Start Page
1332
End Page
1356
Journal / Book Title
SAE Technical Paper Series
Volume
116
Issue
3
Copyright Statement
© 2007 SAE International
Publication Status
Published
Article Number
2007-01-4033