Quantitative planar laser-induced fluorescence imaging of multi-component fuel/air mixing in a firing gasoline-direct-injection engine: Effects of residual exhaust gas on quantitative PLIF

Journal Article · Fri Oct 15 00:00:00 EDT 2010 · Combustion and Flame

DOI:https://doi.org/10.1016/J.COMBUSTFLAME.2010.06.004· OSTI ID:21350366

Williams, Ben; Ewart, Paul ^[1]; Wang, Xiaowei; Stone, Richard ^[2]; Ma, Hongrui; Walmsley, Harold; Cracknell, Roger ^[3]; Stevens, Robert; Richardson, David; Fu, Huiyu; Wallace, Stan ^[4]

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1. Department of Physics, Oxford University, Parks Road, Oxford OX1 3PU (United Kingdom)
2. Department of Engineering Science, Oxford University, Parks Road, Oxford OX1 3PJ (United Kingdom)
3. Shell Global Solutions (UK), Shell Research Centre Thornton, P. O. Box 1, Chester, CH1 3SH (United Kingdom)
4. Jaguar Cars, Engineering Centre, Abbey Road, Whitley, Coventry, CV3 4LF (United Kingdom)

A study of in-cylinder fuel-air mixing distributions in a firing gasoline-direct-injection engine is reported using planar laser-induced fluorescence (PLIF) imaging. A multi-component fuel synthesised from three pairs of components chosen to simulate light, medium and heavy fractions was seeded with one of three tracers, each chosen to co-evaporate with and thus follow one of the fractions, in order to account for differential volatility of such components in typical gasoline fuels. In order to make quantitative measurements of fuel-air ratio from PLIF images, initial calibration was by recording PLIF images of homogeneous fuel-air mixtures under similar conditions of in-cylinder temperature and pressure using a re-circulation loop and a motored engine. This calibration method was found to be affected by two significant factors. Firstly, calibration was affected by variation of signal collection efficiency arising from build-up of absorbing deposits on the windows during firing cycles, which are not present under motored conditions. Secondly, the effects of residual exhaust gas present in the firing engine were not accounted for using a calibration loop with a motored engine. In order to account for these factors a novel method of PLIF calibration is presented whereby 'bookend' calibration measurements for each tracer separately are performed under firing conditions, utilising injection into a large upstream heated plenum to promote the formation of homogeneous in-cylinder mixtures. These calibration datasets contain sufficient information to not only characterise the quantum efficiency of each tracer during a typical engine cycle, but also monitor imaging efficiency, and, importantly, account for the impact of exhaust gas residuals (EGR). By use of this method EGR is identified as a significant factor in quantitative PLIF for fuel mixing diagnostics in firing engines. The effects of cyclic variation in fuel concentration on burn rate are analysed for different fuel injection strategies. Finally, mixture distributions for late injection obtained using quantitative PLIF are compared to predictions of computational fluid dynamics calculations. (author)

• OSTI ID: 21350366
• Journal Information: Combustion and Flame, Vol. 157, Issue 10; Other Information: Elsevier Ltd. All rights reserved; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
33 ADVANCED PROPULSION SYSTEMS
DIRECT INJECTION ENGINES
GASOLINE
AIR
FLUORESCENCE
QUANTUM EFFICIENCY
CALIBRATION
MIXTURES
MIXING
CYLINDERS
EXHAUST GASES
COMPUTERIZED SIMULATION
FLUID MECHANICS
FUEL-AIR RATIO
DISTRIBUTION
IMAGES
VARIATIONS
WINDOWS
DEPOSITS
FORECASTING
SIGNALS
VOLATILITY
Quantitative PLIF
Fuel/air mixing
Gasoline engines
Exhaust gas residuals