Diesel Spray Impinging on a Flat Wall, Part I: Characteristics of Adhered Fuel Film in an Impingement Diesel Spray

Ko, Kyung-Nam; Arai, Masataka

doi:10.1615/atomizspr.v12.i56.120

Cited by 18 publications

(14 citation statements)

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“…After a quick evaluation based on experiments about vaporisation rates of heptane droplets gently deposited on a plate, and the use of a 1D model that predicts lifetime of liquid films [13], we can say that almost twice the mass was present at the end of injection. This gives a new value for Km = 29%, which is in line with results previously obtained in the literature [11,14,15,16]. Then, the thickness at the end of injection is obtained using Eq 12:…”

Section: Resultssupporting

confidence: 79%

Spreading model for wall films generated by high-pressure sprays

Lamiel

Lamarque

Hélie

et al. 2017

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

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This paper presents a new model developed to predict the area of wall films that may develop in gasoline direct injection engines (GDI). In a always more restrictive legislation on gas emissions the injection process in internal combustion (IC) engines has been highlighted as a domain of great concern in order to satisfy these requirements. Many spray wall interactions models exist in literature and are included in different CFD tools. Most often they are based on the sum of single drop-wall impacts. The specificity of the present model lies in its simplicity and the way the film is treated globally. Here its propagation is predicted using a balance between the momentum given by the spray and the viscous shear stress. Jointly with the theoretical model, an experimental set-up has been built up, an optical measurement technique called Refractive Index Matching method is used to follow the development of the wall film. It has been found that the area of the wall film is proportional to the duration of injection, while the distance between the injector and the wall has not shown many influence on the evolution of area. The influence of the injection pressure has also been identified, when the pressure is doubled the radius of the film is multiplied by 3 √ 2. Eventually the model predicts that film thickness decreases as fuel pressure rises. Keywords automotive sprays, spray-wall impingement, refractive index matching method IntroductionFuel impingement in an internal combustion (IC) engine is a critical phenomenon. Despite progresses in gasoline direct injection (GDI) sytem design, fuel spray-wall impingement still happens for certain engine conditions and leads to liquid deposits. These wall films on the piston or the cylinder liner strongly affect mixture formation and entail bad local mixture homogeneity. This has been identified as a major source of pollutant emissions, especially particulate matter [1,2]. As a consequence, it is essential to have a good understanding of these spray-wall interactions and identify the key factors to keep them under control.

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Section: Resultssupporting

confidence: 79%

Spreading model for wall films generated by high-pressure sprays

Lamiel

Lamarque

Hélie

et al. 2017

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

View full text Add to dashboard Cite

show abstract

“…Okawa et al [98,99], extended the experimental conditions of Cossali to a wider range of Weber numbers and film thickness, and they observed a slight influence of the film thickness on the number of secondary droplets. The authors then fitted a correlation for the number of secondary droplets, valid for normal impacts, (N S ) wet to their own experimental data and to that reported by Stow and Stainer [66]: 4 We. In addition, analysis of the results reported by Okawa et al [116], allows the argument that this relation is better suited for impacts onto liquid films with d f < 2.…”

Section: Referencementioning

confidence: 99%

“…For example, high injection pressures are known to extend the area of impact [1,2] and increase the droplet impact velocity, but they also improve the number flux of small size droplets which are prone to interact with the surrounding air and therefore with vaporization and mixing [3]. But these effects are offset by increased surrounding pressures [1,2,4,5] and may be mitigated for injections of long duration [6], when the amount of liquid adhering to the surface increases and splash is inhibited [7]. Buildup of liquid film can be avoided by short injection duration, which can lead to the recommended use of splitting injection strategies, e.g.…”

Section: Spray Impingement Phenomena In Ic Enginesmentioning

confidence: 99%

“…Vaporization particularly reduces the rate of impacting liquid [3], although the effect may differ for high-pressure DirectInjection Spark Ignition (DISI) sprays, e.g. Senda et al [7], and diesel sprays [2,4,5].…”

Section: Spray Impingement Phenomena In Ic Enginesmentioning

confidence: 99%

“…4 We, which was identified in Section 2 as an important parameter governing droplet disintegration, can be argued to stand for impacts onto a liquid film. In fact, the correlation proposed by Yarin and Weiss [55], and further developed by other authors to establish the boundary between spread and disintegration [92][93][94], is usually expressed as U crit > ðs lv =rÞ 0:25 ðnÞ 0:125 ðf Þ 0:375 , but can be rewritten in the form 4 We >> 1, considering f w U 0 /D 0 . Experimental data reported in the literature [62,95,96], are in relatively good agreement with this threshold condition.…”

Section: Droplet Disintegration At Impact Onto a Liquid Filmmentioning

confidence: 99%

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