Flame front analysis of ethanol, butanol, iso-octane and gasoline in a spark-ignition engine using laser tomography and integral length scale measurements

Aleiferis, P.G.; Behringer, Markus

doi:10.1016/j.combustflame.2015.09.008

Cited by 65 publications

(22 citation statements)

References 78 publications

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“…Differences between fuels for their fuel specific injection duration were small, with average length scales over the measurement areas between 4-6 mm. Ethanol had typically largest average scales and butanol lowest (nevertheless, parallel work established a manifestation of even those small length scale differences on the flame front structure past ignition timing [38]). Table 4.…”

Section: Integral Length Scale Profilingmentioning

confidence: 99%

“…However, the resulting flow field for each fuel and condition was used to investigate effects on combustion and published elsewhere with some interesting correlations between the modulated integral length scales for each fuel and the local structure of their flame front [38], an exercise that fortified confidence in the importance of the effects quantified here.…”

Section: Integral Length Scales Of Turbulence With Fuel Injectionmentioning

confidence: 99%

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Modulation of integral length scales of turbulence in an optical SI engine by direct injection of gasoline, iso -octane, ethanol and butanol fuels

Aleiferis

Behringer

2017

Fuel

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In-cylinder air flow structures are known to play a major role in mixture preparation and engine operating limits for spark-ignition engines. In this paper PIV measurements were undertaken in an optical spark-ignition at 1500 RPM, part-load with 0.5 bar intake plenum pressure. One of the PIV planes was vertical, cutting through the centrally located spark plug (tumble plane). The other plane was horizontal 1 mm below the spark plug ground electrode (swirl plane). The effect of engine head temperature was also examined by using engine-head coolant temperatures of 20 °C and 80 °C. The flow field was examined late in the compression stroke at typical ignition timing. The study was conducted under air-only motoring engine conditions but also under fuelled conditions in the early intake stroke using direct injection of gasoline, iso-octane, ethanol and butanol fuels. The flow field under air-only motored conditions showed velocities between 3-5 m/s predominantly from intake to exhaust. Little differences were observed between hot and cold engine-head temperature; typically ~10% larger mean velocity and turbulent kinetic energy was seen on the intake side. Integral length scales were on the tumble plane between 2-4.5 mm in the vertical and 4-7 mm in the horizontal direction. The swirl view showed scales between 4-10 mm, larger at cold than at hot engine-head conditions. The vertical length scales appeared to be limited by the clearance height, scaling typically by about 10-15%. The horizontal components scaled to the cylinder bore diameter by about 5-12%. The fuel injection process in the early intake stroke led to little differences in the general mean flow structure at ignition timing, except for a small increase in the maximum velocities, ~10%. The turbulent kinetic on the tumble plane was highest towards the exhaust side of the engine under non-fuelled engine conditions but fuel injection resulted in highest values on the intake side. The integral length scales with fuel injection were of the same order of magnitude to those of air only measurements on the tumble plane, but showed distinctly larger areas with length scales up to 9 mm on the swirl plane. Differences between fuels for their fuel specific injection duration were small, with average length scales between 4-6 mm. Ethanol exhibited typically largest scales and butanol smallest.3

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Section: Integral Length Scale Profilingmentioning

confidence: 99%

Section: Integral Length Scales Of Turbulence With Fuel Injectionmentioning

confidence: 99%

Modulation of integral length scales of turbulence in an optical SI engine by direct injection of gasoline, iso -octane, ethanol and butanol fuels

Aleiferis

Behringer

2017

Fuel

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“…The data in Figure 4 indicate that the isooctane achieved a maximum speed of 9260 RPM at 30˚ ± 1˚ BTDC and this optimal The isopropanol achieved a similar maximum speed of 9200 RPM but at a more advanced timing of 35˚ BTDC. It has been widely reported that, in general, alcohols have faster flame propagation speeds compared to isooctane [26] [27]. It was therefore a surprise that the isopropanol demonstrated a need for its ignition position to be advanced, rather than retarded.…”

Section: Resultsmentioning

confidence: 99%

Isopropanol as Fuel for Small Unmanned Aircraft

Poh¹,

Poh²

2017

AAST

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Gasoline engines are increasingly popular for use in small unmanned aircraft requiring endurance due to the specific energy of gasoline (47.3 MJ·kg ) and its cost effectiveness. However, gasoline is volatile and it poses a health hazard. In this work, isopropanol is proposed and investigated as viable fuel for small gasoline engines. Isooctane is used as a benchmark for performance comparison. The field testing reveals that isopropanol offers similar running performance and ease of starting. The maximum output power of isopropanol is surprisingly found to occur at a more advanced ignition timing compared with isooctane. The significant outcome of this study is that isopropanol can readily be used as a replacement fuel for existing engines without the need for any modifications to the ignition module or the engine itself.

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“…The works of Aleiferis & Behringer [49] conducted on the same engine geometry under investigation here, found the integral length scale of turbulence l t at spark timing in each spatial plane to be: l u 2-5 mm, l v 5-8 mm and l w 3-7 mm, thus giving an approximate integral length scale of 5 mm. This is in agreement with a number of other published works.…”

Section: Regimes Of Combustionmentioning

confidence: 99%

“…The laminar flame thickness δ l , was approximated as 0.0185 mm for iso-octane, as presented in [49].…”

Section: Regimes Of Combustionmentioning

confidence: 99%

Numerical Evaluation of Combustion Regimes in a GDI Engine

Beavis

Ibrahim

Malalasekera

2018

Flow Turbulence Combust

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There is significant interest in the gasoline direct-injection engine due to its potential for improvements in fuel consumption but it still remains an area of active research due to a number of challenges including the effect of cycle-by-cycle variations. The current paper presents the use of a 3D-CFD model using both the RANS and LES turbulence modelling approaches, and a Lagrangian DDM to model an early fuel injection event, to evaluate the regimes of combustion in a gasoline direct-injection engine. The velocity fluctuations were investigated as an average value across the cylinder and in the region between the spark plug electrodes. The velocity fluctuations near the spark plug electrodes were seen to be of lower magnitude than the globally averaged fluctuations but exhibited higher levels of cyclic variation due to the influence of the spark plug electrode and the pent-roof geometry on the in-cylinder flow field. Differences in the predicted flame structure due to differences in the predicted velocity fluctuations between RANS and LES modelling approaches were seen as a consequence of the inherently higher dissipation levels present in the RANS methodology. The increased cyclic variation in velocity fluctuations near the spark plug electrodes in the LES predictions suggested significant variation in the relative strength of the incylinder turbulence and that may subsequently result in a thickening of the propagating flame front from cycle-to-cycle in this region. Throughout this paper, the numerical results were validated against published experimental data of the same engine geometry under investigation.

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Flame front analysis of ethanol, butanol, iso-octane and gasoline in a spark-ignition engine using laser tomography and integral length scale measurements

Cited by 65 publications

References 78 publications

Modulation of integral length scales of turbulence in an optical SI engine by direct injection of gasoline, iso -octane, ethanol and butanol fuels

Modulation of integral length scales of turbulence in an optical SI engine by direct injection of gasoline, iso -octane, ethanol and butanol fuels

Isopropanol as Fuel for Small Unmanned Aircraft

Numerical Evaluation of Combustion Regimes in a GDI Engine

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