A study on diesel spray tip penetration and radial expansion under reacting conditions

Payri, Raúl; García-Oliver, José M; Xuan, Tiemin; Bardi, Michele

doi:10.1016/j.applthermaleng.2015.07.042

Cited by 71 publications

(82 citation statements)

References 17 publications

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“…After that, penetration difference of reacting spray between two facilities is larger than that of non-reacting spray. As for ECN case, reacting spray tip starts accelerating and penetrates faster than the nonreacting one after the radial expansion becoming stable [9][10][11]. One the other hand, a slower tip penetration in the reacting case compared to the non-reacting one is obtained in the present engine tests, as shown in Figure 16.…”

Section: Reacting Spray Analysissupporting

confidence: 52%

“…This can be explained from different factors, such as aerodynamic forces, vortex and more air entrainment, brought by the airflow might be able to lead to a wider radial expansion compared with the non-reacting one, because of lower density within reacting spray. Figure 16.Comparison of tip penetration with ECN data [11] under reacting conditions at SA1500 point…”

Section: Reacting Spray Analysismentioning

confidence: 99%

“…However, this is compensated by the strong initial increase in radial width. This stage is defined as 'stabilization phase' in reference [11]. After that, penetration difference of reacting spray between two facilities is larger than that of non-reacting spray.…”

Section: Reacting Spray Analysismentioning

confidence: 99%

“…Plenty of experiments are available in the literature either from constant-volume vessels or constant pressure ones. Detailed analysis on the effects of different operating conditions (gas density, ambient temperature, oxygen concentration) and injection pressure on the vapor penetration [1,2], liquid length [3,4], flame lift-off length [5,6], ignition delay [7,8] or even reacting spray dynamics have been investigated [9][10][11]. Thanks to these efforts, the mechanism of the mixing and combustion process of quasi-steady diesel sprays is becoming clear.…”

Section: Introductionmentioning

confidence: 99%

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An Experimental Study on Diesel Spray Injection into a Non-Quiescent Chamber

Pastor¹,

García-Oliver²,

García³

et al. 2017

SAE Int. J. Fuels Lubr.

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Visualization of single-hole nozzles into quiescent ambient has been used extensively in the literature to characterize spray mixing and combustion. However in-cylinder flow may have some meaningful impact on the spray evolution. In the present work, visualization of direct diesel injection spray under both non-reacting and reacting operating conditions was conducted in an optically accessible two-stroke engine equipped with a singlehole injector. Two different high-speed imaging techniques, Schlieren and UV-Light Absorption, were applied here to quantify vapor penetration for non-reacting spray. Meanwhile, Mie-scattering was used to measure the liquid length. As for reacting conditions, Schlieren and OH* chemiluminescence were simultaneously applied to obtain the spray tip penetration and flame lift-off length under the same TDC density and temperature. Additionally, PIV was used to characterize in-cylinder flow motion. Results were compared with those from the Engine Combustion Network database obtained under quiescent ambient conditions in a high pressure high temperature vessel. Because of the air flow induced by piston movement, in-cylinder conditions in the two-stroke engine during the spray injection are highly unsteady, which has a significant impact on the spray development and interference on the spray visualization. From the comparison with quiescent data from the Engine Combustion Network, air flow induced by piston movement was found to slow down tip penetration. Moreover, both ignition delay and lift-off length under unsteady flow conditions show less sensitivity with ambient temperature than that of quasi-steady conditions.

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Section: Reacting Spray Analysissupporting

confidence: 52%

Section: Reacting Spray Analysismentioning

confidence: 99%

Section: Reacting Spray Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

An Experimental Study on Diesel Spray Injection into a Non-Quiescent Chamber

Pastor¹,

García-Oliver²,

García³

et al. 2017

SAE Int. J. Fuels Lubr.

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“…The aim of this work is to simulate the spray A by means of the presumed PDF ADF unsteady flamelet model with different chemical mechanisms of interest in order to clear up the implication on the choice of each of them. Experimental results were measured in CPF experimental facility available at CMT-Motores Térmicos [7,8]. This work starts with a brief description of the model and the spray A parametric studies included.…”

Section: Introductionmentioning

confidence: 99%

Influence of the chemical mechanism in the frame of diesel-like CFD reacting spray simulations using a presumed PDF flamelet-based combustion model

González

Oliver

Novella

et al. 2017

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

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The ability of a computational fluid dynamics (CFD) simulation to reproduce the diesel-like reacting spray ignition process and its corresponding flame structure strongly depends on both the fidelity of the chemical mechanism for reproducing the oxidation of the fuel and also on how the turbulence-chemistry interaction (TCI) is modeled. Therefore, investigating the performance of different chemical mechanisms not only in perfect stirred reactors but directly in the diesel-like spray itself is of great interest in order to evaluate their suitability for being further applied to CFD engine simulations. This research work focuses on applying a presumed probability density function (PDF) unsteady flamelet combustion model to the well-known spray A from the Engine Combustion Network (ECN), using three chemical mechanisms widely accepted by the scientific community as a way to figure out the influence of chemistry in the key characteristics of the combustion process in the frame of diesel-like spray simulations. Results confirm that in spite of providing all of them correct trends for ignition delays (ID) and lift-off lengths (LOL), when comparing with experimental results, the structure of the flame presents noticeable differences, especially in the low and intermediate temperatures and high equivalence ratio regions. Consequently, the selection of the chemical mechanism has an impact on the zones of influence of key species as observed in both spatial coordinates and also in the equivalence ratio-temperature maps. These differences are expected to be relevant considering the implications when coupling pollutant emissions models. The analysis of temperature and oxygen concentration parametric studies evidences how the observed differences are consistent and moderately dependent on the ambient conditions. KeywordsCombustion modeling, Chemical mechanism, Spray A, Flamelet IntroductionThe improvement of the combustion technologies in industrial devices, such as diesel engines, in terms of efficiency and pollutant emissions, evidence that a comprehensive knowledge of the processes involved is mandatory. Between the different processes that concur in the energetic transformation, turbulent non-premixed combustion appears as one of the most relevant. Nevertheless, its modeling is a complex issue due to the different length and time scales of the turbulence, the fuel oxidation and the interaction between them [1]. These considerations point out that for a proper modeling of the turbulent non-premixed combustion two main aspects are essential. The first one is the chemical mechanism, that determines the fuel oxidation, while the second one is the turbulence-chemistry interaction (TCI). Promoted by the need of gaining a very detailed knowledge in these issues in diesel spray conditions, the Engine Combustion Network (ECN) has proposed a set of experiments in controlled conditions that shed light for these concerns by means of experiments and numerical simulations. More particularly, the well-known spray A models a die...

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Representative Phenomena of Cyclic Turbulent Combustion in High-Pressure Fuel Sprays

Parker

Agrawal

Bittle

2023

Flow Turbulence Combust

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Cyclic variations in conventional diesel combustion engines can lead to large differences in engine out emissions even at steady operation. This study uses an optically accessible constant-pressure flow chamber to acquire fuel injections in quick succession to analyze mixing, auto-ignition, and combustion of diesel-surrogate n-heptane using multiple high-speed optical diagnostics. Prior studies have utilized fewer injections and/or they rely on analysis of ensemble average behavior. These approaches do not yield information on injection-to-injection variation or provide confidence in utilizing individual injection measurements for high-fidelity computational fluid dynamics(CFD) model validation. In this study, a large set of 500 injections is used to obtain global parameters including liquid length, vapor penetration length, ignition delay time, and lift-off length. Results for multiple injections are presented to illustrate large injection to injection variations. Potential sources for these variations are analyzed to conclude localized, small scale turbulence and rate of injection variations as the likely sources. Then, a statistical method based on z-scores is proposed and implemented to identify instantaneous injections that best represent the bulk data-set of jet boundaries measured independently by three different diagnostics. This synthesis of statistics-guided screening of data set and ensemble-average analysis offers higher confidence for CFD model validation relying upon both a representative single and average injection results.

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A study on diesel spray tip penetration and radial expansion under reacting conditions

Cited by 71 publications

References 17 publications

An Experimental Study on Diesel Spray Injection into a Non-Quiescent Chamber

An Experimental Study on Diesel Spray Injection into a Non-Quiescent Chamber

Influence of the chemical mechanism in the frame of diesel-like CFD reacting spray simulations using a presumed PDF flamelet-based combustion model

Representative Phenomena of Cyclic Turbulent Combustion in High-Pressure Fuel Sprays

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