Advances and challenges in explaining fuel spray impingement: How much of single droplet impact research is useful?

Moreira, A.L.N.; Moita, Ana S.; Panão, Miguel R. Oliveira

doi:10.1016/j.pecs.2010.01.002

Cited by 459 publications

(214 citation statements)

References 156 publications

(356 reference statements)

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“…Besides ambient factors and injection parameters, splashing and spreading after impingement are affected significantly by the wall conditions such as the roughness, texture, liquid film, and wall temperature [12]. Deendarlianto et al [13] studied the influence of wall roughness on the dynamic behavior of single and multiple successive water droplets after impacting the inclined hot plate surface.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on Effect of Wall Roughness and Lubricant Film on the Adhered Fuel Film of N-Butanol-Diesel Blends after Spray Impingement

et al. 2018

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Abstract:The effect of wall roughness with different lubricant film thicknesses on the characteristics of adhered fuel films of diesel-n-butanol blending fuels after spray impingement has been investigated. Four steel plates with different types of roughness (root mean square height-Sq) that were coated with different lubricant film thicknesses (h l ) were used as impinged walls. The experimental conditions included dry walls (h l = 0), semi-wetted walls (SWW) with different thin oil films (0 < h l /Sq < 1), and fully wetted walls (FWW) with a thick lubricant film (h l > Sq). The results indicate that the adhered fuel mass ratio (ε) of blended fuel with 25% n-butanol (B25) was higher than that of blended fuel with 15% n-butanol (B15) under the same conditions. ε increased with an increase in Sq on the dry walls, but, under SWW conditions, it decreased with an increase in oil film thickness. The fuel film morphology was almost unaffected by the change in Sq, but the results implied that the roughness parameter-Skewness (Ssk) exerted a greater impact. The mean thickness h a and accumulated diameter D l of the adhered fuel film increased with an increase in h l , but, under FWW conditions, the effect of the roughness on the adhered film's features was insignificant.

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Section: Introductionmentioning

confidence: 99%

Experimental Investigation on Effect of Wall Roughness and Lubricant Film on the Adhered Fuel Film of N-Butanol-Diesel Blends after Spray Impingement

et al. 2018

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“…A clear example of these limitations is the study of droplet wall/interactions. Despite being studied for more than a century by many researchers as reviewed for instance in [3][4], the complex relation between droplet dynamics and heat transfer is far to be understood. The current knowledge on droplet/wall interactions recognizes wettability as playing a fundamental role in droplet dynamics and heat transfer processes.…”

Section: Introductionmentioning

confidence: 99%

Time resolved thermographic analysis of droplet impacts onto heated surfaces under extreme wetting scenarios

Pontes

Teodori

Moita³

et al. 2017

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

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The present paper explores the use of time resolved infrared IR thermography combined with high-speed imaging to describe the liquid-surface interfacial heat transfer phenomena occurring at droplet/wall interactions. Custom made calibration and post-processing methods are proposed and discussed. The results show that the methodology proposed captures very well particular details on droplet dynamics and heat transfer, allowing to identify air bubble trapping at the impact region as well as the temperature variations at the formation of the rim. Furthermore, the calibration proposed here allowed amending some physically incorrect results that were often obtained with the IR camera's default calibration. The combined analysis of droplet dynamics (e.g. the spreading factor) with the radial temperature profiles, heat flux and cooling effectiveness computation allowed establishing qualitative and quantitative trends on the effect of various parameters on the heat transfer occurring at droplet/wall interactions. Particularly, the effect of the initial surface temperature is observed to play a minor role, as long as it is low enough to prevent the occurrence of boiling. On the other hand, extreme wetting scenarios, such as superhydrophobicity limit the heat transfer between the spreading droplet and the surface. However, the thermal analysis reveals that a major reason for this is not related to the reduced contact time of the droplet on the surface (due to rebound) or air entrapment, but is rather associated to the reduced wetted area caused by the high contact angles.

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“…Many models have been derived with success to describe the different impact regimes (on cold or hot surfaces) and the spreading characteristics of single droplets [4,5,6]. Some of them are commonly used in CFD tools and coupled with a Lagrangian description of the spray [7,8,9].…”

Section: Introductionmentioning

confidence: 99%

“…Some of them are commonly used in CFD tools and coupled with a Lagrangian description of the spray [7,8,9]. Nevertheless, it has been shown that spray-wall impingement implies many phenomena, which cannot be completly described by single droplet-wall impact models [5,10]. Moreover, while available computational power has strongly increased and despite some success, CFD tools sometimes remain expensive to simulate all the different engine conditions, for a first screening or even while optimising injector targeting and injection timings.…”

Section: Introductionmentioning

confidence: 99%

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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Advances and challenges in explaining fuel spray impingement: How much of single droplet impact research is useful?

Cited by 459 publications

References 156 publications

Experimental Investigation on Effect of Wall Roughness and Lubricant Film on the Adhered Fuel Film of N-Butanol-Diesel Blends after Spray Impingement

Experimental Investigation on Effect of Wall Roughness and Lubricant Film on the Adhered Fuel Film of N-Butanol-Diesel Blends after Spray Impingement

Time resolved thermographic analysis of droplet impacts onto heated surfaces under extreme wetting scenarios

Spreading model for wall films generated by high-pressure sprays

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