Large eddy simulation of diesel spray–assisted dual-fuel ignition: A comparative study on two <i>n</i>-dodecane mechanisms at different ambient temperatures

Kannan, Jeevananthan; Gadalla, Mahmoud; Tekgül, Bulut; Karimkashi, Shervin; Kaario, Ossi; Vuorinen, Ville

doi:10.1177/1468087420946551

“…A skeletal chemical mechanism (54 species and 269 reactions) developed by Yao et al [30] for n-dodecane combustion is used. The performance of this mechanism in DF context has been already demonstrated in our earlier studies [25,34,36].…”

Section: D Reacting Shear Layersupporting

confidence: 56%

“…The n-dodecane jet is initially set to 700 K whereas the methane/air mixture is set to 900 K at a constant pressure of 60 bar. The initial conditions corresponding to the ambient premixed mixture are similar to our previous DF spray studies [25,[33][34][35][36][37] as reported in Table 2. The n-dodecane jet moves initially with a relative ve-locity of 10 m/s to the methane/air stream and develops a Kelvin-Helmholtz instability.…”

Section: D Reacting Shear Layermentioning

confidence: 86%

“…The grid size is 4 µm with 256 grid points along each direction, to capture the flame with at least 10 grid points within the laminar flame thickness (δ f ≈ 40 µm). The initial pressure is set at 60 bar and the initial temperature is homogeneous within the entire computational domain at 800 K, which is relevant to the estimated temperature at the most reactive mixture fraction for DF methane/n-dodecane based on 0D simulations [34,36,37,39].…”

Section: D Stratified Combustionmentioning

confidence: 99%

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Fast reactive flow simulations using analytical Jacobian and dynamic load balancing in OpenFOAM

Morev,

Tekgül,

Gadalla

et al. 2021

Preprint

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0

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Detailed chemistry-based computational fluid dynamics (CFD) simulations are computationally expensive due to the solution of the underlying chemical kinetics system of ordinary differential equations (ODEs). Here, we introduce a novel open-source library aiming at speeding up such reactive flow simulations using OpenFOAM, an open-source C++ software for CFD. First, our dynamic load balancing model DLBFoam (Tekgül et al., 2021) is utilized to mitigate the computational imbalance due to chemistry solution in multiprocessor reactive flow simulations. Then, the individual (cell-based) chemistry solutions are optimized by implementing an analytical Jacobian formulation using the open-source library pyJac, and by increasing the efficiency of the ODE solvers by utilizing the linear algebra package LAPACK. We demonstrate the speed-up capabilities of this new library on various combustion problems.These test problems include a 2D turbulent reacting shear layer and 3D stratified combustion to highlight the favorable scaling aspects of the library on ignition/flame front initiation setups for dual-fuel combustion. Furthermore,

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“…The n-dodecane jet is initially set to 700 K whereas the methane/air mixture is set to 900 K at a constant pressure of 60 bar. The initial conditions corresponding to the ambient premixed mixture are similar to our previous DF spray studies 33,[43][44][45][46][47] as reported in Table II. The n-dodecane jet moves initially with a relative velocity of 10 m/s to the methane/air stream and develops a Kelvin-Helmholtz instability.…”

Section: B 2d Reacting Shear Layermentioning

confidence: 92%

“…The performance of this mechanism in DF context has been already demonstrated in our earlier studies. 33,44,46 Figure 5 highlights the DF ignition process in the shear layer, where the n-dodecane jet ignites the surrounding mixture. It is observed that the first-stage ignition from low-temperature chemistry develops primarily within the n-dodecane jet near the mixing layer.…”

Section: B 2d Reacting Shear Layermentioning

confidence: 99%

Fast reactive flow simulations using analytical Jacobian and dynamic load balancing in OpenFOAM

Morev

¹

,

Tekgül

²

,

Gadalla

³

et al. 2022

Self Cite

View full text Add to dashboard Cite

Detailed chemistry-based computational fluid dynamics (CFD) simulations are computationally expensive due to the solution of the underlying chemical kinetics system of ordinary differential equations (ODEs). Here, we introduce a novel open-source library aiming at speeding up such reactive flow simulations using OpenFOAM, an open-source software for CFD. First, our dynamic load balancing model by Tekg€ ul et al. ["DLBFoam: An open-source dynamic load balancing model for fast reacting flow simulations in OpenFOAM," Comput. Phys. Commun. 267, 108073 (2021)] is utilized to mitigate the computational imbalance due to chemistry solution in multiprocessor reactive flow simulations. Then, the individual (cell-based) chemistry solutions are optimized by implementing an analytical Jacobian formulation using the open-source library pyJac, and by increasing the efficiency of the ODE solvers by utilizing the standard linear algebra package. We demonstrate the speed-up capabilities of this new library on various combustion problems. These test problems include a two-dimensional (2D) turbulent reacting shear layer and three-dimensional (3D) stratified combustion to highlight the favorable scaling aspects of the library on ignition and flame front initiation setups for dual-fuel combustion. Furthermore, two fundamental 3D demonstrations are provided on nonpremixed and partially premixed flames, viz., the Engine Combustion Network Spray A and the Sandia flame D experimental configurations, which were previously considered unfeasible using OpenFOAM. The novel model offers up to two orders of magnitude speed-up for most of the investigated cases. The openly shared code along with the test case setups represent a radically new enabler for reactive flow simulations in the OpenFOAM framework.

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A Numerical Study on Premixed Turbulent Planar Ammonia/Air and Ammonia/Hydrogen/Air Flames: An Analysis on Flame Displacement Speed and Burning Velocity

Tamadonfar

¹

,

Karimkashi

²

,

Kaario

³

et al. 2023

Flow Turbulence Combust

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The economic storage and transportation of ammonia ($$\hbox {NH}_3$$ NH 3 ), and its capability to be thermally decomposed to hydrogen ($$\hbox {H}_2$$ H 2 ) make it a potential carbon-free synthetic fuel for the future. To comprehend the fundamental characteristics of $$\hbox {NH}_3$$ NH 3 as a primary fuel enriched with $$\hbox {H}_2$$ H 2 under low turbulent premixed flame conditions, three quasi direct numerical simulations (quasi-DNS) with detailed chemistry and the mixture-averaged transport model are conducted under decaying turbulence herein. The Karlovitz number is fixed to 4.28 for all the test conditions. The blending ratio ($$\alpha$$ α ), specifying the hydrogen concentration in the ammonia/hydrogen mixture, varies from 0.0 to 0.6. The results reveal that the mean value of the density-weighted flame displacement speed ($$S_{\textrm{d}}^{*}$$ S d ∗ ) is similar to (higher than) the unstrained premixed laminar burning velocity ($$S_{\textrm{L}}^{0}$$ S L 0 ) for $$\hbox {NH}_3/$$ NH 3 / air flame ($$\hbox {NH}_3/\hbox {H}_2/$$ NH 3 / H 2 / air flames). Furthermore, the performance of two extrapolation relations for estimating $$S_{\textrm{d}}^{*}$$ S d ∗ as linear and non-linear functions of flame front curvature is discussed thoroughly. The performances of both models are almost similar when evaluating the data near the leading edge of the flame. However, the non-linear one offers more accurate results near the trailing edge of the flame. The results show that the mean flame stretch factor increases with increasing the blending ratio, suggesting that the mean flamelet consumption velocity deviates from $$S_{\textrm{L}}^{0}$$ S L 0 by enriching the mixture with $$\hbox {H}_2$$ H 2 . The mean value of the local equivalence ratio ($$\phi$$ ϕ ) for the turbulent $$\hbox {NH}_3/$$ NH 3 / air flame is almost equal to its laminar counterpart, while it deviates significantly for $$\hbox {NH}_3/\hbox {H}_2/$$ NH 3 / H 2 / air flames. In addition, the local equivalence ratio for the flame front with positive curvature values is higher than the negatively curved regions for $$\hbox {NH}_3/\hbox {H}_2/$$ NH 3 / H 2 / air flames due to $$\hbox {H}_2$$ H 2 preferential diffusion. Furthermore, the results indicate that hydrogen is consumed faster in positively curved regions compared to the negatively curved zones due to enhanced reaction rates of specific chemical reactions.

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Large eddy simulation of diesel spray–assisted dual-fuel ignition: A comparative study on two n-dodecane mechanisms at different ambient temperatures

Cited by 15 publications

References 53 publications

Fast reactive flow simulations using analytical Jacobian and dynamic load balancing in OpenFOAM

Fast reactive flow simulations using analytical Jacobian and dynamic load balancing in OpenFOAM

Fast reactive flow simulations using analytical Jacobian and dynamic load balancing in OpenFOAM

A Numerical Study on Premixed Turbulent Planar Ammonia/Air and Ammonia/Hydrogen/Air Flames: An Analysis on Flame Displacement Speed and Burning Velocity

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