Effects of Charge Motion Control During Cold Start of SI Engines

Lee, Dongkun; Heywood, John B.

doi:10.4271/2006-01-3399

Cited by 13 publications

(9 citation statements)

References 14 publications

(10 reference statements)

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“…On the contrary to CO and NO x emissions, HC emissions depend on spark timings. [8,9] It is clear that the retarded ignition timing decreases the concentration of THC. Generally, two major parameters that determine HC emissions are flame temperature and duration of combustion.…”

Section: Emission Concentrationmentioning

confidence: 97%

A study on characteristics and control strategies of cold start operation for improvement of harmful exhaust emissions in SI engines

et al. 2008

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Emission regulations for automobiles have become more stringent and the improvement of emission during cold start has been a major key issue to meet these regulations. Among many kinds of factors that affect cold start operation, ignition timing is crucial to improve emission characteristics due to the influence on exhaust gas temperature. Recent progress in variable valve timing allows optimized valve event strategies under various ranges of engine operating conditions including cold start. This study investigates effects of ignition and exhaust valve timing on exhaust gas temperature, combustion stability and emission characteristics through cold start bench tests of an SI engine.Experimental results show that exhaust valve timings and ignition timings significantly affect exhaust gas temperature and stability of engine operation under cold start condition. Exhaust valve timing also affects CO and NO x emission due to changes in residual gas fraction of the combustion chamber. Ignition timing mainly affects exhaust gas temperature and HC emission. A control strategy, advanced exhaust valve timing and retarded ignition, is plausible in order to achieve reduction of exhaust emission while maintaining stability under cold start operation of SI engines.

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Section: Emission Concentrationmentioning

confidence: 97%

A study on characteristics and control strategies of cold start operation for improvement of harmful exhaust emissions in SI engines

et al. 2008

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“…Moreover, volumetric efficiency is not necessarily reduced. In this sense, adjustable deflectors are an interesting option for enhancing and controlling the charge motion and turbulence at low load [21,30,31].…”

Section: Geometric Modifications: Flow Deflectorsmentioning

confidence: 99%

“…The fuel burning rate is directly related to the turbulence intensity [4,[18][19][20][21], which could be controlled depending on the engine regime. Steady tests are the first step in developing valve timing strategies that allow control of the in-cylinder flow [5,13,[22][23][24][25].…”

Section: Tumble Testsmentioning

confidence: 99%

In-cylinder flow control in a four-valve spark ignition engine: numerical and experimental steady rig tests

Ramajo

Zanotti

Nigro

2011

Proceedings of the Institution of Mechanical Engineers, Part D:

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Computational fluid dynamic (CFD) simulations and experimental steady flow tests (flow discharge, swirl, and tumble) were carried out to study the in-cylinder flow in a commercial four-valve spark ignition engine. The present investigation was aimed at analysing and controlling the generation of macro-vortex structures (swirl and tumble) during the inlet process. A comparative study of the most commonly employed tumble benches along with in-house design was performed, the last showing some advantages with respect to the others. The outcomes from the simulations were in agreement with experimental results. Mainly, the tumble generation rate was in general proportional to the valve lift. However, tumble was reduced drastically at medium valve lift due to a change in the vortex pattern. A stagnation zone was observed between inlet valves. CFD calculations successfully captured this tumble-fall effect, which was related to characteristic changes in the vortex pattern downstream of the inlet valves at medium valve lift. This affects tumble production without affecting the mass flowrate efficiency. Finally, at high valve lifts the tumble production and the vortex pattern were recovered. The capability of the cylinder head to induce swirl, tumble, or combined swirl-tumble by modifying the valve timing or by introducing adjustable flow deflectors was evaluated using CFD. Several valve timing strategies were analysed: some of them produced significant swirl, but introduced high mass flowrate losses. On the other hand, adjustable flow deflectors were shown to be an interesting alternative to induce swirltumble at low load and to improve tumble at high load.

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“…This is because the use of the tumble mixture-motion plate provided more turbulence, which effectively enhanced the mixing during the intake process. Lee and Heywood (2006) studied the effects of CMCV on combustion characteristics and hydrocarbon emissions. The authors concluded that CMCV improved mixture preparation due to increased swirl and tumble intensities which enhanced fuel transport, distribution, and evaporation.…”

Section: Introductionmentioning

confidence: 99%

High-Speed Flow and Combustion Visualization to Study the Effects of Charge Motion Control on Fuel Spray Development and Combustion Inside a Direct-Injection Spark-Ignition Engine

Mittal¹,

Hung²,

Zhu³

et al. 2011

SAE Int. J. Engines

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An experimental study is performed to investigate the effects of charge motion control on in-cylinder fuel-air mixture preparation and combustion inside a direct-injection sparkignition engine with optical access to the cylinder. Highpressure production injector is used with fuel pressures of 5 and 10 MPa. Three different geometries of charge motion control (CMC) device are considered; two are expected to enhance the swirl motion inside the engine cylinder whereas the third one is expected to enhance the tumble motion. Experiments are performed at 1500 rpm engine speed with the variation in fuel injection timing, fuel pressure and the number of injections. It is found that swirl-type CMC devices significantly enhance the fuel-air mixing inside the engine cylinder with slower spray tip penetration than that of the baseline case without CMC device. Combustion images show that the flame growth is faster with CMC device compared to the similar case without CMC device.

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Effects of Charge Motion Control During Cold Start of SI Engines

Cited by 13 publications

References 14 publications

A study on characteristics and control strategies of cold start operation for improvement of harmful exhaust emissions in SI engines

A study on characteristics and control strategies of cold start operation for improvement of harmful exhaust emissions in SI engines

In-cylinder flow control in a four-valve spark ignition engine: numerical and experimental steady rig tests

High-Speed Flow and Combustion Visualization to Study the Effects of Charge Motion Control on Fuel Spray Development and Combustion Inside a Direct-Injection Spark-Ignition Engine

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