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 Scania CV AB

Format:

Conference/Event

Author/Creator:

Dembinski, Dembinski, author.

Conference Name:

SAE International Powertrains, Fuels and Lubricants Meeting (2011-08-30 : Kyoto, Japan)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2011

Summary:

Spray and mixture formation in a compression ignition engine isof paramount importance for diesel combustion. In engine transientoperation, when the load increases rapidly, the combustion systemneeds to handle low lambda (λ) operation while avoiding highparticle emissions. Single-cylinder tests were performed toevaluate the effect of differences in cylinder flow on combustionand emissions at typical low λ transient operation. The tests wereperformed on a heavy-duty single-cylinder test engine with LotusActive Valve Train (AVT) controlling the inlet airflow. Therequired swirl number (SN) and tumble were controlled by applyingdifferent inlet valve profiles and opening either both inlet valvesor only one or the other. The operating point of interest wasextracted from engine transient conditions before the boostpressure was increased and investigated further at steady stateconditions. The AVT enabled the resulting SN to be controlled atbottom dead centre (BDC) from ~0.3 to 6.8 and tumble from ~0.5 to4. The fuel injection pressure was varied from 500 bar up to 2000bar, with increments of 500 bar, for each SN and tumble setting. Noexhaust gas recirculation was used in following tests. GT-POWER wasused to calculate SN, tumble, and turbulent intensity with thedifferent valve settings. The input data for the GT-POWER flowcalculations were measured in a steady-state flow rig withhoneycomb torque measurement.The main conclusion of this study was that the air flowstructure in the cylinder, characterized by SN, tumble, andturbulent intensity, has a significant effect on the resultingengine combustion and emissions for the investigated range of fuelinjection pressures. By increasing SN above 3, while maintainingtumble at low levels, the engine could be run with richer air/fuelmixtures without further increasing smoke emissions at injectionpressures 1000 bar and above. Also, NOx emissionsdecreased at λ below 1.3; ignition delay time decreased at highertumble and turbulent levels; and higher levels of swirl resulted inmore rapid combustion, decreasing smoke emissions at injectionpressures over 1000 bar. Smoke emissions increase at higher enginespeeds (above 1200 rpm) and high SN (above 6). The results of thisstudy demonstrate that the mixing process controlled by in-cylinderflow (swirl and tumble) has a dominant effect on combustion

Notes:

Vendor supplied data

Publisher Number:

2011-01-1830

Access Restriction:

Restricted for use by site license