Structure of evaporating single- and multicomponent fuel sprays for 2nd generation gasoline direct injection

Zigan, Lars; Schmitz, Ingo; Flügel, A.; Wensing, Michael; Leipertz, Alfred

doi:10.1016/j.fuel.2010.08.001

Cited by 77 publications

(37 citation statements)

References 40 publications

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“…The larger enthalpy of vaporization, viscosity and surface tension of ethanol likely yields greater droplet sizes than for primary reference fuels or gasoline as indicated by the hollow cone spray measurements of several fuels [17]. This behaviour has been confirmed for multihole sprays of E85 and gasoline at atmospheric conditions [18].…”

Section: Ethanolmentioning

confidence: 71%

“…The soot pattern is thought to stem from the liquid jets in the portion of the hollow cone spray impinging on the piston crown depositing a greater amount of liquid fuel on the piston compared to the less dense and lower momentum fuel spray between the jets. Mie scattering measurements in the radial plane by [17] 15 [mm] from the injector at a time corresponding to 7 [CAD] after the start of injection at ω = 1500 [CAD] showed the a fuel spray density distribution reminiscent of the piston crown soot pattern visible in the OH * chemiluminescence. The hollow ellipses piston crown soot pattern is similar to the soot deposits shown by [23] on a flat quartz piston crown in a piston bowl after spray guided stratified combustion of E85 using an 8-hole fuel injector.…”

Section: Oh* Chemiluminescence and Soot Incandescencementioning

confidence: 99%

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In cylinder visualization of stratified combustion of E85 and main sources of soot formation

Johansen

Hemdal

2015

Fuel

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The combustion process and soot formation in spark ignited spray guided stratified combustion of E85 was investigated in a single cylinder optical engine with direct injection of fuel using an outward opening piezo actuated injector. The effect of engine rotation frequency, fuel quantity, injection sequence and ignition timing was studied. Combustion, soot formation and soot oxidation was analysed using cylinder pressure measurements, images recorded using high speed video cameras, the flame emission spectrum and OH * chemiluminescence and soot incandescence imaging. A maximum injection duration was found to exist for direct ignition of the fuel spray. Engine rotation frequency had little effect on the initial and maximum rate of combustion. The maximum rate of combustion decreased with increasing cycle fuel mass when a single injection was used. The rate of combustion and indicated mean effective pressure increased and the combustion variability decreased when the single injection was split into multiple injections in close succession to deliver the same total fuel mass and the last fuel spray was ignited. Ignition of the first fuel spray resulted in a more pronounced change. The absence of soot incandescence during the initial flame propagation suggested flame propagation in a partially mixed fuel and air mixture with stoichiometric to fuel lean regions. A single fuel injection resulted in piston pool fires due to fuel spray impingement on the piston and was the primary source of soot formation. The pool fires persisted until after conditions favourable to oxidation of the soot had ended. Soot formation in the gas phase occurred while favourable soot oxidation conditions existed and was efficiently oxidized. The magnitude of the piston pool fires was reduced using multiple injections. The reduction is attributed to a reduction of the fuel spray penetration length and a smaller effective injection orifice area, resulting in a shorter total duration of fuel spray impingement on the piston crown. Soot formation occurred primarily in the gas phase when the first of two fuel sprays was ignited and persisted due to the second fuel spray entering an existing flame leading to fuel rich combustion.

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Section: Ethanolmentioning

confidence: 71%

Section: Oh* Chemiluminescence and Soot Incandescencementioning

confidence: 99%

In cylinder visualization of stratified combustion of E85 and main sources of soot formation

Johansen

Hemdal

2015

Fuel

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“…An outward opening piezo actuated GDI injector (Bosch type) was used during the experiments and mounted at the top of the spray chamber. The outward opening needle creates a hollow cone spray shape with vorticies [9][10][11][12][13]. The injector driver supplies a certain voltage over the piezo stack, which expands rapidly and acts on the needle.…”

Section: Experiments Setupmentioning

confidence: 99%

Imaging of gasoline-like sprays with planar laser-induced exciplex fluorescence using a stereoscopic imaging system

Andersson

Yamaguchi²,

Wang

2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

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The role of the fuel injection systems in direct injected gasoline engines is to achieve a suitable fuel vapor distribution, homogeneous or with some degree of stratification, while avoiding unwanted effects such as wall wetting. Planar laser-induced exciplex fluorescence (PLIEF) is a method suitable for the characterization of such sprays since it enables separate imaging of both vapor and liquid phase of fuel simultaneously. In this study a hollow-cone spray generated with an outwards-opening piezo-actuated injector is investigated, with the injector mounted in a constant volume, constant pressure spray chamber with quartz windows, providing a controlled steady test environment. N-hexane is used as surrogate fuel of gasoline, together with exciplex-forming fluorescence tracers -fluorobenzene and diethylmethylamine. Fluorescence excitation is carried out with a parallel laser sheet from the fourth harmonic light of a Nd:YAG-laser (266 nm) running at 10 Hz. Exciplex fluorescence images from liquid phase and monomer fluorescence spray images from vapor phase can be acquired by a single UV-sensitive CMOS camera equipped with a stereoscope having filters selectively transmitting monomer fluorescence at 295 nm and exciplex fluorescence at 355 nm. Since the fluorescence is strongly quenched by oxygen, most of the experiments were carried out in a nitrogen atmosphere. Images were recorded during the injection and at various time steps after the end of the injection, and typical spray development for this type of injector was observed, i.e. the fuel forms an expanding cone, the sheet breaks up to form a vortex structure and the vortices continue to expand after the end of the injection. Fuel vapor is firstly observed at the same locations as the liquid drops, and is then accumulated into the center of the vortices. In addition, penetration of liquid phase and vapor phase are found to be very similar. Various injection pressures have been tested, which shows that increasing the fuel pressure from 10 to 20 MPa results in a larger vortex structure. The fuel evaporation can be followed by studying the evolution of the monomer and exciplex fluorescence as a function of time. At room temperature the vaporization is found to be very slow, but above 40°C there is a noticeable presence of vapor at the end of the injection, and at higher temperatures, the vaporization goes even faster. Keywords Hollow-cone spray, Exciplex LIF, Phase separation, GDI, LIEF IntroductionThe role of the fuel injection systems in direct injected gasoline engines is to achieve a suitable fuel vapor distribution, homogeneous or with some degree of stratification, while avoiding unwanted effects such as wall wetting. Therefore it is desirable to characterize the fuel injection systems and how the fuel vaporizes and becomes dispersed in the combustion chamber, in order to investigate and improve the combustion process. As an extension technique of planar laser-induced fluorescence (LIF), which is proved to be a powerful imaging technique to visual...

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“…Mie Scattering is another laser technique that has been used by [23][24][25][26][27] to investigate the characteristics of sprays generated by flash-boiling, pneumatic atomization, slit, piezo-electric, and port fuel injectors respectively. While Laser Induced Fluorescence (LIF) was used to visualize spray atomization [28][29], in addition to the Nd:YAG laser [14,21,[30][31][32][33][34][35][36][37] and other laser techniques mentioned in [12,[38][39][40][41][42][43][44][45][46][47][48]. Shadowgraphs are used as well in spray atomization investigations either individually [49][50][51][52] or accompanied by another optical technique such as laser-based techniques [25,28] and high speed camera [53].…”

Section: Introductionmentioning

confidence: 99%

Quantitative spray analysis of diesel fuel and its emulsions using digital image processing

Faik

Zhang

2015

EPJ Web of Conferences

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Abstract. In the present work, an experimental investigation of spray atomization of different liquids has been carried out. An air-assist atomizer operating at low injection pressures valued (4 and 6 bar) has been used to generate sprays of (diesel fuel, 5, 10, and 15% water-emulsified-diesel), respectively. A Photron-SA4 high speed camera has been used for spray imaging at 2000 fps. 20 time intervals (from 5 to 100 ms with 5 ms time difference) are selected for analysis and comparison. Spray macroscopic characteristics (spray penetration, dispersion, cone angle, axial and dispersion velocities) have been extracted by a proposed technique based on image processing using Matlab, where the maximum and minimum (horizontal and vertical) boundaries of the spray are detected, from which the macroscopic spray characteristics are evaluated. The maximum error of this technique is (1.5% for diesel spray) and a little bit higher for its emulsions.

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Structure of evaporating single- and multicomponent fuel sprays for 2nd generation gasoline direct injection

Cited by 77 publications

References 40 publications

In cylinder visualization of stratified combustion of E85 and main sources of soot formation

In cylinder visualization of stratified combustion of E85 and main sources of soot formation

Imaging of gasoline-like sprays with planar laser-induced exciplex fluorescence using a stereoscopic imaging system

Quantitative spray analysis of diesel fuel and its emulsions using digital image processing

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