This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Swirl and Injection Pressure Impact on After-Oxidation in Diesel Combustion, Examined with Simultaneous Combustion Image Velocimetry and Two Colour Optical Method
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 08, 2013 by SAE International in United States
Annotation ability available
After-oxidation in Heavy Duty (HD) diesel combustion is of paramount importance for emissions out from the engine. During diffusion diesel combustion, lots of particulate matter (PM) is created. Most of the PM are combusted during the after-oxidation part of the combustion. Still some of the PM is not, especially during an engine transient at low lambda. To enhance the PM oxidation in the late engine cycle, swirl together with high injection pressure can be implemented to increase in-cylinder turbulence at different stages in the cycle. Historically swirl is known to reduce soot particulates. It has also been shown, that with today's high injection pressures, can be combined with swirl to reduce PM at an, for example, engine transient. The mechanism why the PM engine out is reduced also at high injection pressures is however not so well understood. In this work flow field data during combustion and after-oxidation together with soot and temperature measurements was combined to examine how flow field affects soot formation and oxidation.
Swirl number was varied together with injection pressure and the engine tests were done in a HD optical engine. The load was set to 10 bar & 20 bar IMEP at low lambda without EGR, typically transient load points. A high speed colour camera captures picture of the combustion seen through a glass piston-bowl. The flow field was extracted with combustion image velocimetry (CIV) that traces the glowing soot particulates (or the light luminosity difference) by cross correlation between two pictures from the high speed colour camera. From the same pictures the KL factor and flame temperature were simultaneously calculated with the 2-colour method. Both CIV and the 2-colour method are line of sight optical methods that catches flow, soot and temperature from the light observed through the piston.
It was found that in the after-oxidation part of the cycle, the flow in the piston bowl deviates strongly from solid body rotation (that can be assumed to be the case before injection). With increased injection pressure this deviation from solid body rotation increased at constant swirl number. When swirl number was increased, the deviation from solid body rotation increased even further. This seems to be an important factor during the after-oxidation part of the combustion by amplifying the turbulence. The flame temperature together with KL factor (a measure of soot density inside the cylinder) was also influenced when the flow field in the cylinder was changed. With increased injection pressure, from 500 bar to 1000 bar, the maximum KL was amplified during combustion with 50%, but the measured tail pipe soot was decreasing from 1.22 FSN to 0.49 FSN. This together with increased solid body deviation for the 1000 bar case, at the after-oxidation part of the combustion, leads to the conclusion: The flow field during the late part of the cycle has strong impact on tail pipe soot emissions. What was created during the diffusion combustion has less impact on the tail pipe soot compared to the flow field effects during after-oxidation.
CitationDembinski, H. and Angstrom, H., "Swirl and Injection Pressure Impact on After-Oxidation in Diesel Combustion, Examined with Simultaneous Combustion Image Velocimetry and Two Colour Optical Method," SAE Technical Paper 2013-01-0913, 2013, https://doi.org/10.4271/2013-01-0913.
- Dembinski , Henrik & Ångström , Hans-Erik An Experimental Study of the Influence of Variable In-Cylinder Flow, Caused by Active Valve Train, on Combustion and Emissions in a Diesel Engine at Low Lambda Operation JSAE 201109083
- Chartier , Clément Spray Processes in Optical Diesel Engines, Air-Entrainment and Emissions, u.o. PhD thesis Lund university 2012 978-91-7473-297-9
- Aronsson , Ulf Processes in Optical Diesel Engines, Emissions Formation and Heat Release, u.o. PhD thesis Lund university 2011 978-91-747473-116-3
- Warnatz , J , Maas , U & Dibble , R.W. Combustion, Physical and Chemical Fundamentals, Modeling and Simulation, Experiments, Pollutant Formation 4th Edition. 3-540-25992-9
- Dembinski , H. and Angstrom , H. Optical Study of Swirl during Combustion in a CI Engine with Different Injection Pressures and Swirl Ratios Compared with Calculations SAE Technical Paper 2012-01-0682 2012 10.4271/2012-01-0682
- Dembinski , Henrik Flow measurements using combustion image velocimetry in diesel engines Licentiate thesis TRITA - MMK 2012 03 1400-1179 ISRN/KTH/MMK/R-12/03-SE
- Phantom Cameras http://www.phantomcameras.com/
- AVL www.avl.com
- Winterbone , J.H and Horlock D.E. The Thermodynamics and Gas Dynamics of Internal Combustion Engines Volume II 0-19-856212-8
- Hampson , G. and Reitz , R. Two-Color Imaging of In-Cylinder Soot Concentration and Temperature in a Heavy-Duty DI Diesel Engine with Comparison to Multidimensional Modeling for Single and Split Injections SAE Technical Paper 980524 1998 10.4271/980524
- Larsson , A. Optical Studies in a DI Diesel Engine SAE Technical Paper 1999-01-3650 1999 10.4271/1999-01-3650
- Svensson , K. , Mackrory , A. , Richards , M. , and Tree , D. Calibration of an RGB, CCD Camera and Interpretation of its Two-Color Images for KL and Temperature SAE Technical Paper 2005-01-0648 2005 10.4271/2005-01-0648
- Schmidradler , Dieter Temperaturmessung im Verbrennungsraum eines Dieselmotors mittels RGB-Kamera Wien 1999 Doktorial thesis Technischen Universität Wien Matrikelnummer: 8826156
- Pastor , J. , García , J. , Pastor , J. , and Buitrago , J. Analysis Methodology of Diesel Combustion by Using Flame Luminosity, Two-Colour Method and Laser-Induced Incandescence SAE Technical Paper 2005-24-012 2005 10.4271/2005-24-012
- Lavision http://www.lavision.de/
- Pope , Stephen B. Turbulent flows Cambridge University Press 2000 978-0-59125-6
- Lindström , M. and Ångström , H. A Study of In-Cylinder Fuel Spray Formation and its Influence on Exhaust Emissions Using an Optical Diesel Engine SAE Technical Paper 2010-01-1498 2010 10.4271/2010-01-1498