Flame structure and burning velocity of ammonia/air turbulent premixed flames at high Karlovitz number conditions

Fan, Qingshuang; Liu, Xin; Xu, Leilei; Subash, Arman Ahamed; Brackmann, Christian; Aldén, Marcus; Bai, Xue‐Song; Li, Zhongshan

doi:10.1016/j.combustflame.2021.111943

Cited by 38 publications

(11 citation statements)

References 40 publications

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“…For instance, Doan et al 74,75 have reported that eddies larger than 2 δ L contribute less than 10% to the total tangential strain rate computed along such a surface. It is worth stressing, however, that the PSR model requires a small ratio of Δ / δ L to resolve highly non-linear spatial variations of reaction rates, localized to narrow zones, 32–46 rather than to resolve wrinkles of the zone surface, created by small-scale turbulent eddies. The former task requires significantly better resolution.…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, recent experimental and Direct Numerical Simulation (DNS) data reviewed elsewhere 32–34 show that, even in very intense turbulence, combustion can still be localized to narrow spatial zones, with magnitudes of fluctuations of temperature and mixture concentrations being, therefore, large, see also the latest measurements 35–38 and DNS 39–46 studies. Furthermore, as shown recently, 32 even the aforementioned Damköhler’s hypothesis is consistent with existence of thin reaction zones and, hence, with large fluctuations of temperature and species concentrations.…”

Section: Introductionmentioning

confidence: 96%

“…Furthermore, as shown recently, 32 even the aforementioned Damko¨hler's hypothesis is consistent with existence of thin reaction zones and, hence, with large fluctuations of temperature and species concentrations. In other words, (i) in order for the stirred reactor (thickened flame, or broken reaction zone) regime to exist (if any), turbulence should be much more intense than believed earlier and (ii) mixture non-uniformities can be significant even at small spatial scales under conditions of the cited studies, [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46] thus, requiring very fine meshes when adapting the PSR model in RANS computations or LES of highly turbulent combustion.…”

Section: Introductionmentioning

confidence: 99%

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A priori test of perfectly stirred reactor approach to evaluating mean fuel consumption and heat release rates in highly turbulent premixed flames

Lipatnikov

2023

International Journal of Engine Research

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Unsteady three-dimensional Direct Numerical Simulation (DNS) data obtained earlier by Dave et al. ( J Fluid Mech 2020; 884: A46) from a statistically planar and one-dimensional, highly turbulent, moderately lean hydrogen-air flame propagating in a box are processed to perform a priori test of perfectly stirred reactor model. The test aims in particularly at estimating mesh resolution (or filter width within large eddy simulation framework) required to neglect variations in the temperature and mixture composition within a computational cell when evaluating mean (or filtered) fuel consumption and heat release rates. For this purpose, fuel consumption and heat release rates sampled directly from the DNS data and averaged over a cube of width [Formula: see text] are compared with fuel consumption and heat release rates calculated using the temperature and species concentrations averaged over the same cube. Moreover, turbulent burning velocities computed by integrating the former and latter rates are compared with one another. A ratio of [Formula: see text] to a laminar flame thickness [Formula: see text] is varied from 0.44 to 1.8. The obtained results indicate that the tested simple approach performs reasonably well (poor) if [Formula: see text] ([Formula: see text], respectively). This result is further supported by directly filtering fuel consumption rate in a laminar premixed flame. The values of the thickness [Formula: see text], calculated using detail chemical mechanisms for different fuels under elevated temperatures and pressures associated with combustion in piston engines, indicate that it is difficult to satisfy the constraint of [Formula: see text] in contemporary unsteady multidimensional numerical simulations of turbulent burning in such engines.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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A priori test of perfectly stirred reactor approach to evaluating mean fuel consumption and heat release rates in highly turbulent premixed flames

Lipatnikov

2023

International Journal of Engine Research

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“…Due to increased interest in the combustion characteristics of flames under extremely turbulent conditions, turbulent NH 3 combustion studies were conducted for very strong turbulence conditions. Fan et al 84 examined turbulent combustion under large turbulence Karlovitz number conditions up to 1008 using a similar type of burner as the Michigan Hi-Pilot burner. 85 They investigated turbulent burning velocity, flame surface density, and flame front area for NH 3 -air premixed flames using NH and OH using planar laser-induced fluorescence (PLIF) images.…”

Section: Turbulent Combustionmentioning

confidence: 99%

“…Authors could not find very recent publications on NH 3 boilers and furnaces at a practical scale not already featured in review articles. However, fundamental or laboratory-scale research is very active, especially on NH 3 -coal ,− and NH 3 MILD ,− combustion (only including studies published in 2022 and 2023).…”

Section: Nh3 In Practical Devicesmentioning

confidence: 99%

Mini Review of Ammonia for Power and Propulsion: Advances and Perspectives

Guiberti,

Pezzella,

Hayakawa

et al. 2023

Energy Fuels

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Ammonia is a molecule that has been essential to human activities for centuries. It is widely used as a feedstock for fertilizers, industrial chemicals, and emissions after-treatment systems. The properties of ammonia have led to its interest as a carrier for hydrogen in energy applications. The combustion of ammonia for power and propulsion offers direct applications of this molecule in energy and transportation applications. However, there are significant challenges related to ammonia combustion, including low flammability and potentially high emissions. Blending of ammonia with hydrogen or hydrocarbons offers opportunities to improve combustibility. This mini review discusses challenges related to ammonia combustion and current state-of-the-art approaches to overcoming these challenges with research into chemical kinetics, laminar and turbulent flames, and engine and turbine systems. This paper seeks to introduce and summarize recent results on ammonia combustion by highlighting pertinent aspects of this rich and rapidly increasing body of information.

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Effect of Turbulence and Diffusional–Thermal Instability on Hydrogen‐Rich Syngas Turbulent Premixed Flame

Zhang,

Li,

et al. 2023

Energy Tech

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As a kind of fuel with low‐carbon emissions, hydrogen‐rich syngas has a large resource potential and is a promising alternative energy resource. A series of experiments in a constant volume combustion bomb are carried out to investigate the effects of turbulence and diffusional–thermal (DT) instability on a hydrogen‐rich syngas turbulent premixed flame. The flow field in the constant volume combustion bomb is calibrated, and the turbulent flow field's homogeneity and isotropy were investigated. The effects of different speeds of fan (1366–4273 rpm), hydrogen fractions (55%–95%), pressures (1.0–3.0 bar), and equivalence ratios (0.6–1.0) on the hydrogen‐rich syngas turbulent premixed flame are studied. According to the analyses, the flow field in the experimental device exhibits good homogeneous and isotropic characteristics. With the increase of turbulence intensity, equivalence ratio, hydrogen fraction, or pressure, the turbulent flame propagation speed increases gradually. As the hydrogen fraction increases or the equivalence ratio decreases, the effective Lewis number decreases, and the effect of DT instability on the flame increases. The research in this article is crucial for the clean and efficient utilization of hydrogen‐rich syngas and the design of related burners.

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Flame structure and burning velocity of ammonia/air turbulent premixed flames at high Karlovitz number conditions

Cited by 38 publications

References 40 publications

A priori test of perfectly stirred reactor approach to evaluating mean fuel consumption and heat release rates in highly turbulent premixed flames

A priori test of perfectly stirred reactor approach to evaluating mean fuel consumption and heat release rates in highly turbulent premixed flames

Mini Review of Ammonia for Power and Propulsion: Advances and Perspectives

Effect of Turbulence and Diffusional–Thermal Instability on Hydrogen‐Rich Syngas Turbulent Premixed Flame

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