Optical Study of Swirl during Combustion in a CI Engine with Different Injection Pressures and Swirl Ratios Compared with Calculations Royal Institute of Technology

Format:

Conference/Event

Author/Creator:

Dembinski, Dembinski, author.

Contributor:

Angstrom, Hans-Erik

Conference Name:

SAE 2012 World Congress & Exhibition (2012-04-24 : Detroit, Michigan, United States)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2012

Summary:

Spray and mixture formation in a compression-ignition engine isof paramount importance in the diesel combustion process. In anengine transient, when the load increases rapidly, the combustionsystem needs to handle low λ operation without producing high NOxemissions and large amounts of particulate matter. By changing thein-cylinder flow, the emissions and engine efficiency are affected.Optical engine studies were therefore performed on a heavy-dutyengine geometry at different fuel injection pressures and inletairflow characteristics. By applying different inlet port designsand valve seat masking, swirl and tumble were varied. In the enginetests, swirl number was varied from 2.3 to 6.3 and the injectionpressure from 500 to 2500 bar. To measure the in-cylinder flowaround TDC, particle image velocimetry software was used toevaluate combustion pictures. The pictures were taken in an opticalengine using a digital high-speed camera. Clouds of glowing sootparticles were captured by the camera and traced with particleimage velocimetry software. The velocity-vector field from thepictures was thereby extracted and a mean swirl number wascalculated. The swirl number was then compared with 1D simulationprogram GT-POWER and CFD-based correlations. The GT-POWERsimulations and CFD-based correlation calculations were initiatedfrom steady-state flow bench data on tested cylinder heads.The main conclusions from this study were that the mean swirlnumbers, evaluated with the PIV software from combustion picturesaround TDC, agreed with CFD-based correlations and the low swirlnumbers also correlated with the 1D-simulation program. Most of theinduced swirl motion survives the compression and combustion, whilethe induced tumble does not survive to the late combustion phase.The tumble however, disturbs the swirl motion and offsets the swirlcenter. This offset survives the compression and combustion. Thediesel sprays that are injected symmetrically in the combustionchamber are thereby exposed to the swirl asymmetrically. This studyalso shows that the angular velocity at different piston bowl radiideviates from solid body rotation. The angular velocity is highercloser to the center and decreases to be at the lowest value at theouter piston bowl edge. When the injection pressure is increased,the deviation from solid body rotation increases due to sprayeffects

Notes:

Vendor supplied data

Publisher Number:

2012-01-0682

Access Restriction:

Restricted for use by site license