Impinging Jets of Fuel on a Heated Surface: Effects of Wall Temperature and Injection Conditions

Montanaro, Alessandro; Allocca, Luigi; Lazzaro, Maurizio; Meccariello, Giovanni

doi:10.4271/2016-01-0863

Cited by 15 publications

(11 citation statements)

References 25 publications

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“…The exposure time was 12 μs, for both signals. The post-processing of the images followed the algorithm presented by Montanaro et al 4 The analysis considered that due to the symmetry of the spray–wall interaction observed, the wall temperature effect on the vaporization could be sensed in all the directions of the spray as is assumed by many authors in the literature 4,8,45 when the liquid thickness and width are analyzed.…”

Section: Methodsmentioning

confidence: 99%

“…3 However, it is recognized that the deposition of fuel films on the combustion chamber surfaces is a significant source of particulate formation in GDI engines. 4–7 In order to reduce the particle number (PN) and unburnt hydrocarbons (UHCs) due to flame–film interaction, many authors have tried to improve the understanding of events occurring before, during, and after ignition. Spray–wall interaction is an event that occurs before ignition and that promotes the fuel film generation inside the combustion chamber.…”

Section: Introductionmentioning

confidence: 99%

“…Spray–wall interaction in a real engine involves many parameters, such as the operational regime of the engine (load and speed), the injection strategy, injection pressure, the nature (roughness, chemical composition) and temperature of the wall, physico-chemical properties of the fluid, and the ambient conditions. 4,8 In order to simplify the vaporization process of this interaction, some studies replaced the liquid jet with single droplets, enabling the Nukiyama/Leidenfrost temperatures and wetting regimes to be identified. 9–13 Recently, the formation of fuel films inside and outside the impingement region has gained more attention.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Impact of gasoline direct injection fuel films on exhaust soot production in a model experiment

Roque

Foucher

Lamiel

et al. 2019

International Journal of Engine Research

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The fuel films that can be generated during the injection process in gasoline direct injection engines are the most important factor in carbon particle mass and number. They also have an influence on combustion chamber and injector tip deposits. A model experiment was set up to study a liquid film, its evaporation, and combustion with soot generation on a metal plate in realistic engine conditions. The experiment was conducted in a dedicated constant volume vessel. A liquid fuel injection system (with injection pressures up to 100 bar) directs the spray onto a plate with a controlled temperature in the range of 80 °C–200 °C. The resulting liquid film and vaporization process were studied when subjected to interaction with a laminar spherical flame. A blend of four components was used as a gasoline surrogate. The liquid film spreading, thickness, and evaporation rates were initially measured in ambient conditions. Mie scattering and schlieren measurements in the chamber conditions returned a qualitative correlation of the vaporized area with the surface temperature. Fluorescence of the light and heavy fuel components was used to quantify the influence of the vaporization process on soot production. Simultaneous measurements of natural luminosity and KL factor were analyzed to understand the process of soot production. The results showed a critical wall temperature of 120 °C at which the maximum quantity of soot is generated, which can be due to the quantity and composition of fuel film in interaction with the entrainment flows generated during combustion.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Impact of gasoline direct injection fuel films on exhaust soot production in a model experiment

Roque

Foucher

Lamiel

et al. 2019

International Journal of Engine Research

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“…Schlieren imaging, as a qualitative line-of-sight imaging technique, also visualizes the flow of gaseous fuel. Montanaro et al visualized both the liquid and gaseous fuel during spray-wall interaction in a quiescent chamber for different wall temperatures by schlieren and Mie-scatter imaging [25,26].…”

Section: Introductionmentioning

confidence: 99%

Imaging of Fuel-Film Evaporation and Combustion in a Direct-Injection Model Experiment

Jüngst¹,

Kaiser²

2019

SAE Technical Paper Series

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Late-evaporating liquid fuel films within the combustion chamber are considered a major source of soot in gasoline direct-injection engines. In this study a direct-injection model experiment was developed to visualize and investigate the evaporation of fuel films and their contribution to soot formation with different diagnostic techniques. A mixture of isooctane (surrogate fuel) and toluene (fluorescent tracer) is injected by a multi-hole injector into a wind tunnel with an optically accessible test section. Air flows continuously at low speed and ambient pressure through the test section. Some of the liquid fuel impinges on the quartz-glass windows and forms fuel films. Combustion is initiated by a pair of electrodes within the fuel/airmixture. The turbulent flame front propagates through the chamber and ignites pool fires near the fuel films, leading to locally sooting combustion. Laser-induced fluorescence (LIF) of the toluene, excited by laser pulses at 266 nm, is used to image the fuel-film thickness and to visualize the fuel vapor, while laser-induced incandescence (LII), excited at 1064 nm, is used to visualize soot. In complementary line-of-sight imaging, the natural flame luminosity, mainly from soot incandescence, is captured with a high-speed camera and schlieren imaging, combining visualization of the fuel vapor and the sooting flame. The LIF images show that the fuel films remain on the wall surface long after the flame front has passed. The evaporation rate of the individual fuel films seems to be unaffected by combustion, indicating that conductive heat transfer from the wall is the limiting factor in evaporation. The visualization of both natural flame luminosity and LII show that soot formation occurs in small regions but always close to the fuel films.

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“…Hsieh et al [23] reported that a lower temperature surface led to faster growth of the deposit area in a spray burner. Montanaro et al [24] found that at first the increase of impinging surface temperature could decrease the spread of the liquid film but further increases beyond the Leidenfrost point caused an increased spread.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation on heat transfer of n-pentane spray impingement on piston surface

Zhou

Murad

Tian

et al. 2018

Applied Thermal Engineering

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Fuel spray impingement on piston surfaces is a concern because it can cause particulate exhaust emissions from gasoline direct injection (GDI) engine. Transient heat transfer plays an important role that directly influences liquid film evaporation and its lifetime. In this paper, the effects of injection temperature, injection pressure, piston temperature and impact distance on n-pentane spray impingement heat transfer were fully examined. Results showed that increasing the piston temperature could increase the rate of heat transfer with a larger surface temperature reduction and a higher heat flux, which led to a shorter liquid film lifetime on the piston surface. Increasing the fuel injection temperature helped to improve atomization of the fuel spray, reduce the penetration distance and mitigate impact, which in turn led to reduced surface cooling and less liquid film on the piston surface. A decrease in impact distance and an increase in injection pressure both caused an increase in surface temperature reduction and heat flux but a decrease in the liquid film residence time. The dimensionless heat flux in terms of Biot and Fourier numbers presented a high similarity during the rapid cooling stage. A dimensionless correlation was formed to quantify this fast time-varying heat transfer behaviour.

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Impinging Jets of Fuel on a Heated Surface: Effects of Wall Temperature and Injection Conditions

Cited by 15 publications

References 25 publications

Impact of gasoline direct injection fuel films on exhaust soot production in a model experiment

Impact of gasoline direct injection fuel films on exhaust soot production in a model experiment

Imaging of Fuel-Film Evaporation and Combustion in a Direct-Injection Model Experiment

Experimental investigation on heat transfer of n-pentane spray impingement on piston surface

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