Analysis of Water Droplet Interaction with Turbulent Premixed and Spray Flames Using Carrier Phase Direct Numerical Simulations

Concetti, Riccardo; Haßlberger, Josef; Chakraborty, Nilanjan; Klein, Markus

doi:10.1080/00102202.2023.2182192

Cited by 6 publications

(1 citation statement)

References 38 publications

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“…In other words, we consider the droplet to be a lumped sphere that reaches a uniform constant temperature profile throughout its volume infinitely fast, still varying with time. Although the reported set of assumptions may appear simplistic, such models are used even in recent years in most real-world applications, including CFD codes, both in unsteady Reynolds-averaged Navier-Stokes (uRANS) Fossi et al (2015); Cavalieri et al (2023); Lucchese et al (2024) and large eddy simulations (LES) Esclapez et al (2017); Noh et al (2018); Domingo-Alvarez et al (2020); Benajes et al (2022) approaches, and even in direct numerical simulations (DNS) studies Ciottoli et al (2020); Wang et al (2021); Concetti et al (2023); Liberatori et al (2024).…”

Section: Droplet Evaporation Modelmentioning

confidence: 99%

Evaluation of non-ideal fluid modeling for droplet evaporation in jet-engine-like conditions

Cavalieri,

Liberatori,

Blandino

et al. 2024

Preprint

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Mid-century climate neutrality targets for the aviation industry foster the development of ultra-high overall pressure ratio jet engines. Consequently, comprehensive numerical models driving the design process must tackle the severe thermodynamic conditions expected to occur during the various flight operational phases. In the current study, we present a cost-effective framework for addressing droplet vaporization phenomena in jet-engine-relevant conditions, leveraging real-fluid thermophysical modeling and high-pressure vapor-liquid equilibrium interfacial thermodynamics. We evaluate the impact of a non-ideal fluid approach on predicting the evaporation process of a single n-dodecane droplet in air, mimicking operating conditions relevant to aero-engines. For the conditions examined, the numerical results indicate that adopting a real-fluid thermodynamic treatment results in a deviation of the droplet vaporization rate from an ideal-fluid approach, for which we have outlined the thermodynamic states that lead to mixture non-ideality. Notably, we envisage the most impactful model discrepancies in transport property estimation, thus affecting the heat and mass transfer rates. Lastly, we analyze and quantify the role of the detailed phase equilibrium model in the droplet evaporation process, assessing its actual impact for the conditions of interest, and discussing the cost-effectiveness in commonly computational fluid dynamics tools.

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Section: Droplet Evaporation Modelmentioning

confidence: 99%

Evaluation of non-ideal fluid modeling for droplet evaporation in jet-engine-like conditions

Cavalieri,

Liberatori,

Blandino

et al. 2024

Preprint

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On the Chemical Effect of Steam Addition to Premixed Hydrogen Flames with Respect to $$\text {NO}_\text {x}$$ Emissions and Flame Speed

Concetti,

Hasslberger,

Sattelmayer

et al. 2024

Flow Turbulence Combust

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The present work analyses the effect of water vapour addition on $${\text {NO}_\text {x}}$$ NO x emissions of premixed hydrogen flames. In doing so, the adiabatic flame temperature is maintained by increasing the equivalence ratio, or alternatively increasing the unburned gas temperature, for increasing levels of water loading. Thus, it is possible to elucidate the changes in $${\text {NO}_\text {x}}$$ NO x production at constant-temperature conditions when the mixture is diluted with water. A consistent reduction of $${\text {NO}_\text {x}}$$ NO x emissions for increasing water dilution can be observed from 1-D premixed freely propagating flame simulations. Regarding the chemical kinetics effect of water vapour, the relative importance of different third-body reactions is examined by modifying the corresponding water collision efficiencies individually. For the chemical mechanism adopted, three reactions directly affect the nitrogen chemistry and the remaining relevant reactions are important for the flame structure and radicals concentration. The analysis stresses the importance of indirect effects like the formation and consumption of $$\text {O}$$ O and $$\text {H}$$ H radicals in the pre-heat zone, which enhance the subsequent formation of $${\text {NO}_\text {x}}$$ NO x within the flame. The presence of steam can lead to a reduction of approximately $$50\%$$ 50 % in $${\text {NO}_\text {x}}$$ NO x emissions under conditions close to stoichiometry and high water loading ($$10\%$$ 10 % by mass), compared to scenarios without water addition. Furthermore, the efficiency of water in third-body reactions significantly contributes to an emission reduction, and half of $$\text {NO}$$ NO emissions under the same water loading conditions at high equivalence ratio are observed when the third-body reaction efficiency is activated with respect to the case with zero efficiency. This reduction is primarily attributed to effects on radical concentrations. Finally, the chemical effect via the third-body efficiency of water is examined with respect to flame speed. It turns out that the adiabatic flame temperature plays a key role for the relative influence of the chemical kinetics effect of water dilution. A cross-over temperature is found, below which the chemical effect of water reduces the flame speed, whereas the flame speed is increased above it.

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Evaluation of Non-ideal Fluid Modeling for Droplet Evaporation in Jet-Engine-Like Conditions

Cavalieri,

Liberatori,

Blandino

et al. 2024

Flow Turbulence Combust

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Analysis of Water Droplet Interaction with Turbulent Premixed and Spray Flames Using Carrier Phase Direct Numerical Simulations

Cited by 6 publications

References 38 publications

Evaluation of non-ideal fluid modeling for droplet evaporation in jet-engine-like conditions

Evaluation of non-ideal fluid modeling for droplet evaporation in jet-engine-like conditions

On the Chemical Effect of Steam Addition to Premixed Hydrogen Flames with Respect to $$\text {NO}_\text {x}$$ Emissions and Flame Speed

Evaluation of Non-ideal Fluid Modeling for Droplet Evaporation in Jet-Engine-Like Conditions

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