Computational analysis of end-of-injection transients and combustion recession

Jarrahbashi, Dorrin; Kim, Sayop; Knox, Benjamin W.; Genzale, Caroline L.

doi:10.1177/1468087417701280

Cited by 20 publications

(16 citation statements)

References 21 publications

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“…Studies show that the Yao et al [34] mechanism with 54 species and 268 reactions (referred to as the Yao mechanism) is capable of qualitatively simulating combustion recession. Jarrahbashi et al [15] compared two skeletal chemical mechanisms on modeling combustion recession where the Cai et al [6] mechanism with 57 species and 197 reactions (referred to as the Cai mechanism) was shown to be capable of capturing EOI transients under standard "Spray A" conditions. The Yao mechanism failed to predict combustion recession under the same conditions.…”

Section: Introductionmentioning

confidence: 99%

A Study on Kinetic Mechanisms of Diesel Fuel Surrogate n-Dodecane for the Simulation of Combustion Recession

Fang¹,

Ismail²,

Davy³

2019

SAE Technical Paper Series

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Combustion recession, an end of injection (EOI) diesel spray phenomenon, has been found to be a robust correlation parameter for UHC in diesel LTC strategies. Previous studies have shown that the likelihood of capturing combustion recession in numerical simulations is highly dependent on the details of the low-temperature chemistry reaction mechanisms employed. This study aims to further the understanding of the effects of different chemical mechanisms in the prediction of a reactive diesel spray and its EOI process: combustion recession. Studies were performed under the Engine Combustion Network's (ECN) "Spray A" conditions using the Reynolds-Averaged Navier-Stokes simulation (RANS) and the Flamelet Generated Manifold (FGM) combustion model with four different chemical mechanisms for n-dodecane that are commonly used in the engine simulation communitiesincluding recently developed reduced chemistry mechanisms. The flamelet database for each of the chemical mechanism is generated using two methods: 0D homogeneous reactor (HR) ignition flamelets and 1D igniting counterflow diffusion (ICDF) flamelets. The effect of different tabulation approaches is investigated first following by the discussion of the impact of chemical mechanisms on the prediction of combustion recession. Further discussions include an evaluation of the performance of chemical mechanisms in predicting the most relevant reacting spray characteristics compared to the ECN experimental database: ignition delay time (IDT), flame lift-off length (LOL) and flame reactive region. Results show that the choice of both tabulation method and chemical mechanism play a significant role in initial flame stabilization and end of injection (EOI) transient processes. In general, both tabulation techniques were able to qualitatively capture the flame characteristics before EOI, however ICDF tabulation is better suited for the FGM approach in order to capture combustion recession. Furthermore, the chemical mechanisms studied indicate that mechanisms with stronger low temperature chemistry predictions are more likely to promote combustion recession under an FGM framework.

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Section: Introductionmentioning

confidence: 99%

A Study on Kinetic Mechanisms of Diesel Fuel Surrogate n-Dodecane for the Simulation of Combustion Recession

Fang¹,

Ismail²,

Davy³

2019

SAE Technical Paper Series

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“…Finally, the OH and temperature criteria appear to make very little difference to the predicted lift-off-lengths, with only a minor divergence seen in the Reitz-Diwakar model at 1.25 ms to 1.75 ms, however generally all criteria predict very similar lift-off-lengths. This over-prediction of lift-off-lengths is seen when using both a well stirred reactor model [10,36,37] and the Yao mechanism [9,38].…”

Section: Break-up Model Comparisonmentioning

confidence: 99%

Effect of Liquid Break-Up Model Selection on Simulated Diesel Spray and Combustion Characteristics

Nicholson

Davy

Camm

et al. 2021

SAE Technical Paper Series

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Accurate modelling for spray vapour fields is critical to enable adequate predictions of spray ignition and combustion characteristics of non-premixed reacting diesel sprays. Spray vapour characteristics are in turn controlled by liquid atomization and the KH-RT liquid jet break-up model is regularly used to predict this: with the KH model used for predicting primary break-up given its definition as a surface wave growth model, and the RT model used for predicting secondary break-up due to it being a drag based, stripping model. This paper investigates how the alteration of the switching position of the KH and RT sub-models within the KH-RT model impacts the resulting vapour field and ignition characteristics. The combustion prediction is handled by the implementation of a 54 species, 269 reaction skeletal mechanism utilising a Well Stirred Reactor model within the Star-CD CFD code. Following on from the derivation and implementation of an Ohnesorge based switch between the KH and RT sub-models, this model is now tested in igniting cases for an ndodecane fuelled single holed injection representing the ECN "Spray A" condition, and is compared to the baseline Reitz-Diwakar model. Differences in flame behaviour, particularly within the temperature distribution, are seen and directly traced from the effect of liquid break-up position and model selection, through atomised droplet size distribution and mixture fraction distribution. Different criteria for judging the ignition delays and lift-off-lengths are compared, with all methods predicting very similar results for both models. The KH and RT sub-models are also tested against each other, with heavy instabilities seen when the RT model is solely applied to the spray. This correlates with the instabilities shown in the vapour fields, suggesting the enabling of the RT model near-nozzle is to be avoided.

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“…For the details on Lagrangian-Eulerian spray simulations, the reader is referred to the authors' earlier works. 107,108 The heat transfer on the solid substrate has been neglected here to isolate the behavior of the splashing droplets upon reaching the substrate from evaporation effects. It is noted that small droplets may have a non-Newtonian behavior due to the presence of the nanoparticles; however, as the CNC concentration is low, this study assumed a Newtonian behavior.…”

Section: Governing Equationsmentioning

confidence: 99%

Supercritical CO2-assisted atomization for deposition of cellulose nanocrystals: an experimental and computational study

et al. 2022

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Nanoparticle spray deposition finds numerous applications in pharmaceutical, electronics, manufacturing, and energy industries and has shown great promises in engineering the functional properties of the coated parts. However, current spray deposition systems either lack the required precision in controlling the morphology of the deposited nanostructures or do not have the capacity for large-scale deposition applications. In this study, we introduce a novel spray system that uses supercritical CO2 to assist the atomization process and create uniform micron-size water droplets that are used as cellulose nanocrystal (CNC) carriers. CNCs are selected in this study as they are abundant, possess superior mechanical properties, and contain hydroxyl groups that facilitate interaction with neighboring materials. We fundamentally investigate the effect of different process parameters, such as injection pressure, gas-to-liquid ratio, the axial distance between the nozzle and substrate, and CNC concentration on the final patterns left on the substrate upon evaporation of water droplets. To this end, we show how tuning process parameters control the size of carrier droplets, dynamics of evaporation, and self-assembly of CNCs, which in turn dictate the final architecture of the deposited nanostructures. We will particularly investigate the morphology of the nanostructures deposited after evaporation of micron-size droplets that has not been fully disclosed to date. Different characterization techniques such as laser diffraction, polarized microscopy, and high-resolution profilometry are employed to visualize and quantify the effect of each process parameter. Numerical simulations are employed to inform the design of experiments. Finally, it is shown that the fabricated nanostructures can be engineered based on the size of the carrier droplets controlled by adjusting spray parameters and the concentration of nanoparticles in the injected mixture. Process parameters can be selected such that nanoparticles form a ring, disk, or dome-shaped structure. Moderate operational conditions, simplicity and time efficiency of the process, and use of abundant and biodegradable materials, i.e., water, CNC, and CO2 promote the scalability and sustainability of this method.

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Computational analysis of end-of-injection transients and combustion recession

Cited by 20 publications

References 21 publications

A Study on Kinetic Mechanisms of Diesel Fuel Surrogate n-Dodecane for the Simulation of Combustion Recession

A Study on Kinetic Mechanisms of Diesel Fuel Surrogate n-Dodecane for the Simulation of Combustion Recession

Effect of Liquid Break-Up Model Selection on Simulated Diesel Spray and Combustion Characteristics

Supercritical CO2-assisted atomization for deposition of cellulose nanocrystals: an experimental and computational study

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