Systematic LIF fuel wall film investigation

Schulz, F.; Samenfink, Wolfgang; Schmidt, Jürgen; Beyrau, Frank

doi:10.1016/j.fuel.2016.01.017

Cited by 69 publications

(40 citation statements)

References 25 publications

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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%

“…It has been shown in previous studies that there is less deposited mass when fuel pressure increases [14]. Nevertheless, from 50 to 200bar, changes of K are not expected to be very high.…”

Section: Resultsmentioning

confidence: 77%

“…It could come from the value of Km. Indeed it has been shown [14] that an increase in pressure causes a decrease in the deposited mass.…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

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%

“…It has been shown in previous studies that there is less deposited mass when fuel pressure increases [14]. Nevertheless, from 50 to 200bar, changes of K are not expected to be very high.…”

Section: Resultsmentioning

confidence: 77%

See 1 more Smart Citation

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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show abstract

“…The results presented here show the viability and robustness of the method as well as the possibility of further applications, for example to in-cylinder temperature measurements and heat transfer phenomena analysis or other fast-paced surface heat transfer investigations. Moreover, a combination of such temperature measurements of the wall cooling and film thickness measurements, which were already demonstrated in the works of Henkel et al (2016), Schulz et al (2016), and Schulz et al Spatially averaged surface temperature decrease (T av_bSOI -T av_aSOI ) as a function of the time aSOI for two plates with an average coating thickness of 15 and 31 µm. The spatially averaged temperature before injection T av_bSOI is in both cases 391 K. The T av_aSOI values correspond to the average temperatures in the squared areas shown in Fig.…”

Section: Discussionmentioning

confidence: 84%

Planar measurements of spray-induced wall cooling using phosphor thermometry

et al. 2018

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The wall cooling induced by spray impingement is investigated using phosphor thermometry. Thin coatings of zinc oxide (ZnO) phosphor were applied with a transparent chemical binder onto a steel surface. Instantaneous spatially resolved temperatures were determined using the spectral intensity ratio method directly after the injection of UV-grade hexane onto the surface using a commercial gasoline injector. The investigations showed that 2D temperature measurements with high spatial and shot-to-shot precision of, respectively, 0.5 and 0.6 K can be achieved, allowing the accurate resolution of the cooling induced by the spray. The presence of a liquid film over the phosphor coating during measurements showed no noticeable influence on the measured temperatures. However, in some cases a change in the intensity ratio at the spray impingement area, in the form of a permanent "stain", could be observed after multiple injections. The formation of this stain was less likely with increasing annealing time of the coating as well as lower plate operating temperatures during the injection experiments. Finally, the experimental results indicate a noticeable influence of the thickness of the phosphor coating on the measured spray-induced wall cooling history. Hence, for quantitative analysis, a compromise between coating thickness and measurement accuracy needs to be considered for similar applications where the heat transfer rates are very high.

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“…to detect liquid fuel inside the intake manifold of engines with port fuel injection [41,42] or within the combustion chamber of engines with GDI [37,43,44,45,38]. Fuelfilm thickness measurements by LIF were also done in constant volume chambers at engine-like conditions [46,47,48,49]. However, quantification of the measured film thickness has proven challenging.…”

Section: Methodsmentioning

confidence: 99%

Large Eddy Simulations and Tracer-LIF Diagnostics of Wall Film Dynamics in an Optically Accessible GDI Research Engine

Frapolli¹,

Boulouchos²,

Wright³

et al. 2019

SAE Technical Paper Series

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Large Eddy Simulations (LES) and tracer-based Laser-Induced Fluorescence (LIF) measurements were performed to study the dynamics of fuel wall-films on the piston top of an optically accessible, four-valve pent-roof GDI research engine for a total of eight operating conditions. Starting from a reference point, the systematic variations include changes in engine speed (600; 1,200 and 2,000 RPM) and load (1000 and 500 mbar intake pressure); concerning the fuel path the Start Of Injection (SOI=360°, 390° and 420° CA after gas exchange TDC) as well as the injection pressure (10, 20 and 35 MPa) were varied. For each condition, 40 experimental images were acquired phase-locked at 10° CA intervals after SOI, showing the wall-film dynamics in terms of spatial extent, thickness and temperature. The simulation framework was developed as follows: first, the spray model was calibrated using spray morphology evolution data of the same injector, characterized in a constant volume spray chamber by high-speed shadow imaging. In a second step, the wall impingement and film models were calibrated using the reference condition. With the model constants now fixed, simulations were run for the remaining operating points and results were compared with the experimental data. The simulations captured all trends observed experimentally, with good quantitative in the transient films' spatial extents and thicknesses.

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Systematic LIF fuel wall film investigation

Cited by 69 publications

References 25 publications

Spreading model for wall films generated by high-pressure sprays

Spreading model for wall films generated by high-pressure sprays

Planar measurements of spray-induced wall cooling using phosphor thermometry

Large Eddy Simulations and Tracer-LIF Diagnostics of Wall Film Dynamics in an Optically Accessible GDI Research Engine

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