Advances in Turbulent Combustion

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Mechanical Engineering".

Deadline for manuscript submissions: closed (31 January 2023) | Viewed by 4910

Special Issue Editors


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Guest Editor
Department of Mechanics and Maritime Sciences, Chalmers University of Technology, 412 96 Gothenburg, Sweden
Interests: turbulent reacting flows; laminar flames; ignition; pollutant formation; internal combustion engines
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Guest Editor
Department of Mechanical and Construction Engineering, Northumbria University, Newcastle-upon-Tyne NE1 8ST, UK
Interests: turbulent two-phase and reactive flows; internal combustion engines; mathematical modelling; probability density functions method

Special Issue Information

Dear Colleagues,

Turbulent combustion of gaseous and liquid fuels is widely used for energy conversion in stationary power generation (e.g., industrial gas turbines), aviation (e.g., jet and piston engines), land and maritime transport, and the construction industry, in which piston engines are mostly employed in trucks, offroad vehicles, and cars. Yet, our understanding of the fundamentals of turbulent burning and capabilities for predicting its major characteristics are still limited. This is because turbulent combustion is a result of many highly nonlinear and multiscale phenomena, including thousands of chemical reactions between hundreds of species, molecular and turbulent transport of these species, radiative and convective heat transfer, flows with strong density variations, etc. Depending on local conditions, different phenomena dominate locally and contribute differently to the main variables of interest, such as heat release rate, or to combustion stability and the production of various pollutants. Therefore, there are numerous unresolved issues relevant to turbulent flames and both fundamental and applied studies of these issues are still relevant and highly necessary. This necessity is especially urgent due to the threat of global warming, which poses new challenges for combustion science. In particular, this threat strongly motivates the research and development of efficient energy conversion technologies utilizing chemical energy bound in renewable and either entirely carbon-free fuels, such as hydrogen or ammonia, or fuels with low carbon contents, such as syngas. To adequately respond to challenges, both classical (e.g., efficiency) and new (e.g. emissions of carbon dioxide), combustion science and technology should rapidly be advanced by adopting all available research tools, combining experiments, theory, and numerical simulations and taking new opportunities, e.g., new non-intrusive laser diagnostic techniques with a high spatial or/and temporal resolution or rapid progress in computer simulation technologies and methods. Accordingly, this Special Issue is intended to provide an international forum for researchers from industry and academia to present their ideas and the latest developments the field of turbulent combustion, including developments of new research methods, both experimental and numerical.

Prof. Dr. Andrei Lipatnikov
Prof. Dr. Alexey Burluka
Guest Editors

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Keywords

  • turbulent reacting flows
  • combustion
  • flames
  • modeling
  • numerical simulations
  • experiments
  • internal combustion engines
  • computational fluid dynamics

Published Papers (3 papers)

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Research

21 pages, 9366 KiB  
Article
A Differential Subgrid Stress Model and Its Assessment in Large Eddy Simulations of Non-Premixed Turbulent Combustion
by Roman Balabanov, Lev Usov, Alexei Troshin, Vladimir Vlasenko and Vladimir Sabelnikov
Appl. Sci. 2022, 12(17), 8491; https://doi.org/10.3390/app12178491 - 25 Aug 2022
Cited by 5 | Viewed by 1116
Abstract
We present a new subgrid stress model for the large eddy simulation of turbulent flows based on the solution of transport equations for stress tensor components. The model was a priori term-by-term calibrated against an open DNS database on forced isotropic turbulence (Johns [...] Read more.
We present a new subgrid stress model for the large eddy simulation of turbulent flows based on the solution of transport equations for stress tensor components. The model was a priori term-by-term calibrated against an open DNS database on forced isotropic turbulence (Johns Hopkins University database). After that, it was applied in a large eddy simulation of non-premixed turbulent combustion. To demonstrate the impact of the new subgrid stress model on scalar fields, we excluded the backward effect of heat release on the subgrid stresses, considering an isothermal reaction (i.e., diluted mixture; the density variations associated with chemical heat release can be neglected) and a Burke–Schumann reaction sheet approximation. A periodic box filled with a homogeneous turbulent velocity field and a three-layer top-hat mixture fraction field was studied. Four simulations were performed in which a fixed model for mixture fraction and its variance was combined with either the proposed subgrid stress model or one of the standard models, including Smagorinsky, dynamic Smagorinsky and WALE. Qualitatively correct backscatter was observed in a simulation with the new model. The differences in the statistics of the mixture fraction and reactive component fields caused by the new subgrid stress model were analyzed and discussed. The importance of using an advanced subgrid stress model was highlighted. Full article
(This article belongs to the Special Issue Advances in Turbulent Combustion)
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10 pages, 2815 KiB  
Article
A Transition of Ignition Kernel Delay Time at the Early Stages of Lean Premixed n-Butane/Air Turbulent Spherical Flame Propagation
by Minh Tien Nguyen and Shenqyang (Steven) Shy
Appl. Sci. 2022, 12(8), 3914; https://doi.org/10.3390/app12083914 - 13 Apr 2022
Cited by 2 | Viewed by 1461
Abstract
This paper explores the effects of root-mean-square turbulence fluctuation velocity (u′) and ignition energy (Eig) on an ignition kernel delay time (τdelay) of lean premixed n-butane/air spherical flames with an effective Lewis number Le ≈ 2.1 [...] Read more.
This paper explores the effects of root-mean-square turbulence fluctuation velocity (u′) and ignition energy (Eig) on an ignition kernel delay time (τdelay) of lean premixed n-butane/air spherical flames with an effective Lewis number Le ≈ 2.1 >> 1. Experiments are conducted in a dual-chamber, fan-stirred cruciform burner capable of generating near-isotropic turbulence with negligible mean velocities using a pair of cantilevered electrodes with sharp ends at a fixed spark gap of 2 mm. τdelay is determined at a critical flame radius with a minimum flame speed during the early stages of laminar and turbulent flame propagation. Laminar and turbulent minimum ignition energies (MIEL and MIET) are measured at 50% ignitability, where MIEL = 3.4 mJ and the increasing slopes of MIET with u′ change from gradual to drastic when u′ > 0.92 m/s (MIE transition). In quiescence, a transition of τdelay is observed, where the decrement of τdelay becomes rapid (modest) when Eig is less (greater) than MIEL. For turbulent cases, when applying Eig ≈ MIET, the reverse trend of MIE transition is found for τdelay versus u′ results with the same critical u′ ≈ 0.92 m/s. These results indicated that the increasing u′ could reduce τdelay on the one hand, but require higher Eig (or MIET) on the other hand. Moreover, the rising of Eig in a specific range, where Eig ≤ MIE, could shorten τdelay, but less contribution as Eig > MIE. These results may play an important role to achieve optimal combustion phases and design an effective ignition system on spark ignition engines operated under lean-burn turbulent conditions. Full article
(This article belongs to the Special Issue Advances in Turbulent Combustion)
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20 pages, 11577 KiB  
Article
Multiscale Analysis of Anisotropy of Reynolds Stresses, Subgrid Stresses and Dissipation in Statistically Planar Turbulent Premixed Flames
by Markus Klein, Theresa Trummler, Noah Urban and Nilanjan Chakraborty
Appl. Sci. 2022, 12(5), 2275; https://doi.org/10.3390/app12052275 - 22 Feb 2022
Cited by 3 | Viewed by 1440
Abstract
The characterisation of small-scale turbulence has been an active area of research for decades and this includes, particularly, the analysis of small-scale isotropy, as postulated by Kolmogorov. In particular, the question if the dissipation tensor is isotropic or not, and how it is [...] Read more.
The characterisation of small-scale turbulence has been an active area of research for decades and this includes, particularly, the analysis of small-scale isotropy, as postulated by Kolmogorov. In particular, the question if the dissipation tensor is isotropic or not, and how it is related to the anisotropy of the Reynolds stresses is of particular interest for modelling purposes. While this subject has been extensively studied in the context of isothermal flows, the situation is more complicated in turbulent reacting flows because of heat release. Furthermore, the landscape of Computational Fluid Dynamics is characterised by a multitude of methods ranging from Reynolds-averaged to Large Eddy Simulation techniques, and they address different ranges of scales of the turbulence kinetic energy spectrum. Therefore, a multiscale analysis of the anisotropies of Reynolds stress, dissipation and sub-grid scale tensor has been performed by using a DNS database of statistically planar turbulent premixed flames. Results show that the coupling between dissipation tensor and Reynolds stress tensor is weaker compared to isothermal turbulent boundary layer flows. In particular, for low and moderate turbulence intensities, heat release induces pronounced anisotropies which affect not only fluctuation strengths but also the characteristic size of structures associated with different velocity components. Full article
(This article belongs to the Special Issue Advances in Turbulent Combustion)
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