Potential of the Spray-guided Combustion System in Combination with Turbocharging

Lang, Oliver; Habermann, Knut; Krebber-Hortmann, Karl; Sehr, Andreas; Thewes, Matthias; Kleeberg, Henning; Tomazic, Dean

doi:10.4271/2008-01-0139

Cited by 10 publications

(1 citation statement)

References 2 publications

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“…Ongoing research and development on SGSC engines include higher injection pressures 109–111 and boosted operation (turbo- and/or super-charged) to extend the upper load limit of stratified operation without excessive engine-out soot production. 96,111–114 Multi-pulse injection (up to eight pulses per cycle) is being pursued aggressively both for mixture preparation (combustion stability; NOx, soot, and hydrocarbon emissions) and to avoid fuel impingement on surfaces (spark plug, 115 piston bowl, or cylinder wall). 37,96,114,116 Multi-strike ignition systems 35,37,74,107,114,116 are also being used in combination with these strategies.…”

Section: Sgsc Development Directionsmentioning

confidence: 99%

Invited Review: Combustion instability in spray-guided stratified-charge engines: A review

Fansler

Reuss

Sick

et al. 2015

International Journal of Engine Research

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This article reviews systematic research on combustion instabilities (principally rare, random misfires and partial burns) in spray-guided stratified-charge (SGSC) engines operated at part load with highly stratified fuel -air -residual mixtures. Results from high-speed optical imaging diagnostics and numerical simulation provide a conceptual framework and quantify the sensitivity of ignition and flame propagation to strong, cyclically varying temporal and spatial gradients in the flow field and in the fuel -air -residual distribution. For SGSC engines using multi-hole injectors, spark stretching and locally rich ignition are beneficial. Combustion instability is dominated by convective flow fluctuations that impede motion of the spark or flame kernel toward the bulk of the fuel, coupled with low flame speeds due to locally lean mixtures surrounding the kernel. In SGSC engines using outwardly opening piezo-electric injectors, ignition and early flame growth are strongly influenced by the spray's characteristic recirculation vortex. For both injection systems, the spray and the intake/compression-generated flow field influence each other. Factors underlying the benefits of multi-pulse injection are identified. Unresolved questions include (1) the extent to which piezo-SGSC misfires are caused by failure to form a flame kernel rather than by flame-kernel extinction (as in multi-hole SGSC engines); (2) the relative contributions of partially premixed flame propagation and mixing-controlled combustion under the exceptionally late-injection conditions that permit SGSC operation on E85-like fuels with very low NOx and soot emissions; and (3) the effects of flow-field variability on later combustion, where fuel-air-residual mixing within the piston bowl becomes important.

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