Flow, Mixture Preparation and Combustion in Direct-Injection Two-Stroke Gasoline Engines

Fansler, Todd D.; Drake, Michael C.

doi:10.1007/978-3-540-68901-0_2

Cited by 2 publications

(4 citation statements)

References 84 publications

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“…as they mix with lean, hot post-flame gases. Experimental observations suggestive of later-stage mixing-controlled combustion included heat-release rates proportional to the amount of unburned fuel remaining in the cylinder 28,85 and bright, broadband combustion luminosity typically associated with thermal emission from locally rich, diffusive combustion (in contrast to chemiluminescence from early-stage premixed combustion that is much less intense at visible wavelengths). 28,55,59,86,87 Results suggestive of mixing-controlled combustion have also been found recently for SGSC operation with very late injection of ethanol-dominated fuel blends (Sec.…”

Section: Stable Spray-guided Combustion With Multi-hole Injectorsmentioning

confidence: 99%

“…Some of these programs were extensive in terms of time and resources (e.g. Texaco TCCS, 17–19 Ford FCP and PROCO, 20–22 General Motors DISC, 23–27 and several DI two-stroke designs 28 ). United Parcel Service converted GM six-cylinder truck engines to the TCCS design; field tests in some 500 of their delivery trucks over a 2-year period in the early 1980s 29 showed fuel-economy improvement of 30%–35% relative to the unmodified engine.…”

Section: Introductionmentioning

confidence: 99%

“…The HC emissions, which were a generic issue with these and earlier SC designs, were dominated by overmixing and lean flame quenching at the edges of the fuel cloud. 11,28 Engine-out soot emissions originated predominantly in pool fires fed by liquid fuel films on the piston surface. 32 NOx emissions reduction was—and continues to be—an issue for all SC engines because these engines operate with an overall lean fuel–air ratio, precluding the use of the traditional three-way catalyst that reduces NO in the absence of oxygen in the exhaust stream.…”

Section: Introductionmentioning

confidence: 99%

“…Given the importance of ignition and early-kernel growth to successful combustion (as illustrated for SGSC in Figure 3), earlier studies using optical diagnostics in two-stroke and four-stroke SC engines naturally focused on the fuel concentration near the spark gap. 3,6,11,28,42,43 Although fuel–air equivalence-ratio fluctuations over a sufficiently wide range to inhibit or prevent ignition were detected, there typically was not a simple correlation with combustion stability. 3,6 For example, Ghandhi and Bracco 6 observed that a significant fraction of cycles in a two-stroke SGSC engine had a measured equivalence ratio far leaner than the lean ignitability limit, but nevertheless ignited and burned well.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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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Section: Stable Spray-guided Combustion With Multi-hole Injectorsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Fansler

Reuss

Sick

et al. 2015

International Journal of Engine Research

View full text Add to dashboard Cite

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Combustion Variability Monitoring in Engines Using High-Speed Exhaust Temperature and Pressure Measurements

Bajwa

Patterson²,

Jacobs³

2023

Journal of Engineering for Gas Turbines and Power

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The diagnostic merits of high-speed (HS) exhaust gas temperature and pressure measurements for indexing engine stability and identifying abnormal combustion cycles are explored through experimental investigations on a slow-speed, single-cylinder engine. Exhaust temperature and pressure are measured using a fine wire 50 µm thermocouple and a piezo-resistive pressure transducer, respectively. Synchronously recorded cylinder pressure data is used to continuously index combustion variations, and then anomalous combustion event detection and engine stability monitoring are attempted using HS exhaust temperature and pressure measurements. Two types of abnormal combustion cycles, namely misfiring and overload cycles are used to typify low and high intensity anomalous combustion cycles, respectively. The results demonstrate that if suitable cyclic exhaust pressure and temperature metrics are used, anomalous combustion cycles can be identified, and overall combustion variability levels can be indexed. The comparative diagnostic performance of HS measured exhaust pressure and temperature and slow speed measured exhaust temperature are also discussed. A thermodynamic simulation of the engine and the HS thermocouple is used to provide theoretical support for the discussion by comparing measured and simulated 'actual' exhaust temperature and identifying the flow, heat transfer, and thermodynamic influences that act as limits to the thermocouple's dynamic performance.

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Flow, Mixture Preparation and Combustion in Direct-Injection Two-Stroke Gasoline Engines

Cited by 2 publications

References 84 publications

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

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

Combustion Variability Monitoring in Engines Using High-Speed Exhaust Temperature and Pressure Measurements

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