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Valiev, Damir
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Publications (10 of 36) Show all publications
Adebiyi, A., Alkandari, R., Valiev, D. & Akkerman, V. (2019). Effect of surface friction on ultrafast flame acceleration in obstructed cylindrical pipes. AIP Advances, 9(3), Article ID 035249.
Open this publication in new window or tab >>Effect of surface friction on ultrafast flame acceleration in obstructed cylindrical pipes
2019 (English)In: AIP Advances, ISSN 2158-3226, E-ISSN 2158-3226, Vol. 9, no 3, article id 035249Article in journal (Refereed) Published
Abstract [en]

The Bychkov model of ultrafast flame acceleration in obstructed tubes [Valiev et al., “Flame Acceleration in Channels with Obstacles in the Deflagration-to-Detonation Transition,” Combust. Flame 157, 1012 (2010)] employed a number of simplifying assumptions, including those of free-slip and adiabatic surfaces of the obstacles and of the tube wall. In the present work, the influence of free-slip/non-slip surface conditions on the flame dynamics in a cylindrical tube of radius R, involving an array of parallel, tightly-spaced obstacles of size αR, is scrutinized by means of the computational simulations of the axisymmetric fully-compressible gasdynamics and combustion equations with an Arrhenius chemical kinetics. Specifically, non-slip and free-slip surfaces are compared for the blockage ratio, α, and the spacing between the obstacles, ΔZ, in the ranges 1/3 ≤ α ≤ 2/3 and 0.25 ≤ ΔZ/R ≤ 2.0, respectively. 

For these parameters, an impact of surface friction on flameacceleration is shown to be minor, only 1-4%, slightly facilitating acceleration in a tube with ΔZ/R = 0.5 and moderating acceleration in thecase of ΔZ/R = 0.25. Given the fact that the physical boundary conditions are non-slip as far as the continuum assumption is valid, the presentwork thereby justifies the Bychkov model, employing the free-slip conditions, and makes its wider applicable to the practical reality. Whilethis result can be anticipated and explained by a fact that flame propagation is mainly driven by its spreading in the unobstructed portion ofan obstructed tube (i.e. far from the tube wall), the situation is, however, qualitatively different from that in the unobstructed tubes, wheresurface friction modifies the flame dynamics conceptually.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2019
National Category
Other Mechanical Engineering
Identifiers
urn:nbn:se:umu:diva-158147 (URN)10.1063/1.5087139 (DOI)000462880300151 ()
Available from: 2019-04-14 Created: 2019-04-14 Last updated: 2019-05-23Bibliographically approved
Feng, R., Zhang, R. & Valiev, D. (2019). Effect of thermal gas expansion on the fractal structure of outwardly propagating flames. In: : . Paper presented at 12th Asia-Pacific Conference on Combustion, ASPACC 2019, Fukuoka, Japan, July 1-5, 2019. Combustion Institute
Open this publication in new window or tab >>Effect of thermal gas expansion on the fractal structure of outwardly propagating flames
2019 (English)Conference paper, Oral presentation only (Other academic)
Abstract [en]

The role of Darrieus-Landau instability in forming the fractal structure of the freely propagating expanding flame front is studied numerically by solving the two-dimensional Navier-Stokes equations with one step irreversible Arrhenius reaction. Numerical simulation of the radially expanding flames with Le=1 demonstrates that the temporal dependence of mean radius after a certain critical time instant is corresponding to a power law, in line with previous experimental, numerical and theoretical studies. Influence of gas expansion ratio on power-law exponent and flame surface fractal dimension is the focus of this research. It is shown that the expansion coefficient has an effect on fractal structure of the outwardly propagating flame, confirming the assumption that fractal dimension is not a universal parameter.

Place, publisher, year, edition, pages
Combustion Institute, 2019
National Category
Other Physics Topics
Identifiers
urn:nbn:se:umu:diva-162907 (URN)
Conference
12th Asia-Pacific Conference on Combustion, ASPACC 2019, Fukuoka, Japan, July 1-5, 2019
Available from: 2019-08-30 Created: 2019-08-30 Last updated: 2020-02-24Bibliographically approved
Alkhabbaz, M., Abidakun, O., Valiev, D. & Akkerman, V. (2019). Impact of the Lewis number on finger flame acceleration at the early stage of burning in channels and tubes. Physics of fluids, 31(8), Article ID 083606.
Open this publication in new window or tab >>Impact of the Lewis number on finger flame acceleration at the early stage of burning in channels and tubes
2019 (English)In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 31, no 8, article id 083606Article in journal (Refereed) Published
Abstract [en]

For premixed combustion in channels and tubes with one end open, when a flame is ignited at the centerline at the closed end of the pipe and it propagates toward the open one, significant flame acceleration occurs at an early stage of the combustion process due to formation of a finger-shaped flame front. This scenario is tagged “finger flame acceleration” (FFA), involving an initially hemispherical flame kernel, which subsequently acquires a finger shape with increasing surface area of the flame front. Previous analytical and computational studies of FFA employed a conventional assumption of equidiffusivity when the thermal-to-mass-diffusivity ratio (the Lewis number) is unity (Le = 1). However, combustion is oftentimes nonequidiffusive (Le ≠ 1) in practice such that there has been a need to identify the role of Le in FFA. This demand is addressed in the present work. Specifically, the dynamics and morphology of the Le ≠ 1 flames in two-dimensional (2D) channels and cylindrical tubes are scrutinized by means of the computational simulations of the fully compressible reacting flow equations, and the role of Le is identified. Specifically, the Le > 1 flames accelerate slower as compared with the equidiffusive ones. In contrast, the Le < 1 flames acquire stronger distortion of the front, experience the diffusional-thermal combustion instability, and thereby accelerate much faster than the Le = 1 flames. In addition, combustion in a cylindrical configuration shows stronger FFA than that under the same burning conditions in a 2D planar geometry.

National Category
Other Mechanical Engineering
Identifiers
urn:nbn:se:umu:diva-162173 (URN)10.1063/1.5108805 (DOI)000483888900032 ()2-s2.0-84994806860 (Scopus ID)
Available from: 2019-08-15 Created: 2019-08-15 Last updated: 2019-10-25Bibliographically approved
Kodakoglu, F., Demir, S., Valiev, D. & Akkerman, V. (2019). Towards Descriptive Scenario of a Burning Accident in anObstructed Mining Passage: An Analytical Approach. In: : . Paper presented at 27th International Colloquium on the Dynamics of Explosions and Reactive Systems (ICDERS), July 28th – August 2nd, 2019, Beijing, China (pp. 1-6). Institute for Dynamics of Explosions and Reactive Systems
Open this publication in new window or tab >>Towards Descriptive Scenario of a Burning Accident in anObstructed Mining Passage: An Analytical Approach
2019 (English)Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Institute for Dynamics of Explosions and Reactive Systems, 2019
Keywords
mining passage, explosion, deflagration-to-detonation transition, DDT
National Category
Other Mechanical Engineering
Identifiers
urn:nbn:se:umu:diva-164109 (URN)
Conference
27th International Colloquium on the Dynamics of Explosions and Reactive Systems (ICDERS), July 28th – August 2nd, 2019, Beijing, China
Available from: 2019-10-15 Created: 2019-10-15 Last updated: 2019-10-29Bibliographically approved
Adebiyi, A., Idowu, G., Valiev, D. & Akkerman, V. (2018). Computational simulations of nonequidiffusive premixed flames in obstructed pipes. In: : . Paper presented at 2018 Spring Technical Meeting of the Eastern States Section of the Combustion Institute, ESSCI 2018; Pennsylvania State University, State College; United States; 4 March 2018 through 7 March 2018. West Virginia University
Open this publication in new window or tab >>Computational simulations of nonequidiffusive premixed flames in obstructed pipes
2018 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

The impact of the Lewis number, Le, on the dynamics and morphology of a premixed flame front, spreading through a toothbrush-like array of obstacles in a semi-open channel, is studied by means of the computational simulations of the reacting flow equations with fully-compressible hydrodynamics and Arrhenius chemical kinetics. The computational approach employs a cell-centered, finite-volume numerical scheme, which is of the 2nd-order accuracy in time, 4th-order in space for the convective terms, and of the 2nd-order in space for the diffusive terms. The channels of blockage ratios 0.33∼0.67 are considered, with the Lewis numbers in the range 0.2≤Le≤2.0 employed. It is shown that the Lewis number influences the flame evolution substantially. Specifically, flame acceleration weakens for Le>1 (inherent to fuel-lean hydrogen or fuel-rich hydrocarbon burning), presumably, due to a thickening of the flame front. In contrast, Le<1 flames (such as that of rich hydrogen or lean hydrocarbon) acquire an extra strong folding of the front and thereby accelerate even much faster. The later effect can be devoted to the onset of the diffusional-Thermal combustion instability. © 2018 Eastern States Section of the Combustion Institute. All rights reserved.

Place, publisher, year, edition, pages
West Virginia University, 2018
National Category
Other Mechanical Engineering
Identifiers
urn:nbn:se:umu:diva-158148 (URN)
Conference
2018 Spring Technical Meeting of the Eastern States Section of the Combustion Institute, ESSCI 2018; Pennsylvania State University, State College; United States; 4 March 2018 through 7 March 2018
Available from: 2019-04-14 Created: 2019-04-14 Last updated: 2019-04-15Bibliographically approved
Rutkowski, L., Johansson, A. C., Khodabakhsh, A., Valiev, D., Lodi, L., Yurchenko, S., . . . Foltynowicz, A. (2017). Detection of OH and H2O in an Atmospheric Flame by Near-Infrared Optical Frequency Comb Spectroscopy. In: 2017 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC): . Paper presented at Conference on Lasers and Electro-Optics Europe / European Quantum Electronics Conference (CLEO/Europe-EQEC), JUN 25-29, 2017, Munich, GERMANY. IEEE
Open this publication in new window or tab >>Detection of OH and H2O in an Atmospheric Flame by Near-Infrared Optical Frequency Comb Spectroscopy
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2017 (English)In: 2017 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC), IEEE, 2017Conference paper, Published paper (Refereed)
Abstract [en]

Absorption spectroscopy is attractive for combustion diagnostics because it allows in-situ and calibration-free quantification of reactants/products and thermometry. However, spectra measured at atmospheric pressure in the near-infrared telecom range, where laser sources and optical components are readily available, suffer from strong water interference. Cavity-enhanced optical frequency comb spectroscopy (CE-OFCS) is well suited for detection of other species, as it provides broad bandwidth with high signal-to-noise ratio and resolution, and allows de-convolving the spectra hidden among water transitions. Here we report detection of OH in the presence of H2O in an atmospheric premixed methane/air flat flame by CE-OFCS at 1.57 μm. We demonstrate a new water line list that is more accurate than HITEMP [1] and we isolate the OH lines by dividing spectra taken at different heights above the burner (HABs) to retrieve OH concentration and flame temperature.

Place, publisher, year, edition, pages
IEEE, 2017
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-152156 (URN)10.1109/CLEOE-EQEC.2017.8086912 (DOI)000432564600671 ()978-1-5090-6736-7 (ISBN)
Conference
Conference on Lasers and Electro-Optics Europe / European Quantum Electronics Conference (CLEO/Europe-EQEC), JUN 25-29, 2017, Munich, GERMANY
Funder
Swedish Research Council, 621-2012-3650Swedish Foundation for Strategic Research , ICA12-0031Knut and Alice Wallenberg Foundation, KAW 2015.0159
Available from: 2018-10-01 Created: 2018-10-01 Last updated: 2018-10-01Bibliographically approved
Feng, R., Zhong, H. & Valiev, D. (2017). Influence of gas expansion on the interaction between spatially periodic shear flow and premixed flame. In: : . Paper presented at 11th Asia-Pacific Conference on Combustion, ASPACC 2017; University of Sydney; Sydney; Australia; 10 - 14 December 2017.
Open this publication in new window or tab >>Influence of gas expansion on the interaction between spatially periodic shear flow and premixed flame
2017 (English)Conference paper, Oral presentation with published abstract (Other academic)
National Category
Other Mechanical Engineering
Identifiers
urn:nbn:se:umu:diva-151033 (URN)
Conference
11th Asia-Pacific Conference on Combustion, ASPACC 2017; University of Sydney; Sydney; Australia; 10 - 14 December 2017
Available from: 2018-08-23 Created: 2018-08-23 Last updated: 2018-08-23
Ugarte, O., Bychkov, V., Sadek, J., Valiev, D. & Akkerman, V. (2016). Critical role of blockage ratio for flame acceleration in channels with tightly spaced obstacles. Physics of fluids, 28(9), Article ID 093602.
Open this publication in new window or tab >>Critical role of blockage ratio for flame acceleration in channels with tightly spaced obstacles
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2016 (English)In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 28, no 9, article id 093602Article in journal (Refereed) Published
Abstract [en]

A conceptually laminar mechanism of extremely fast flame acceleration in obstructed channels, identified by Bychkov et al. ["Physical mechanism of ultrafast flame acceleration," Phys. Rev. Lett. 101, 164501 (2008)], is further studied by means of analytical endeavors and computational simulations of compressible hydrodynamic and combustion equations. Specifically, it is shown how the obstacles length, distance between the obstacles, channel width, and thermal boundary conditions at the walls modify flamepropagation through a comb-shaped array of parallel thin obstacles. Adiabatic and isothermal (cold and preheated) side walls are considered, obtaining minor difference between these cases, which opposes the unobstructed channel case, where adiabatic and isothermal walls provide qualitatively different regimes offlame propagation. Variations of the obstructed channel width also provide a minor influence on flamepropagation, justifying a scale-invariant nature of this acceleration mechanism. In contrast, the spacing between obstacles has a significant role, although it is weaker than that of the blockage ratio (defined as the fraction of the channel blocked by obstacles), which is the key parameter of the problem. Evolution of the burning velocity and the dependence of the flame acceleration rate on the blockage ratio are quantified. The critical blockage ratio, providing the limitations for the acceleration mechanism in channels with comb-shaped obstacles array, is found analytically and numerically, with good agreement between both approaches. Additionally, this comb-shaped obstacles-driven acceleration is compared to finger flameacceleration and to that produced by wall friction.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2016
National Category
Other Physics Topics Other Mechanical Engineering Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:umu:diva-125154 (URN)10.1063/1.4961648 (DOI)000384878900016 ()
Funder
Lars Hierta Memorial Foundation, FO2015-0916
Available from: 2016-09-07 Created: 2016-09-07 Last updated: 2018-06-07Bibliographically approved
Rutkowski, L., Johansson, A. C., Valiev, D., Khodabakhsh, A., Tkacz, A., Schmidt, F. M. & Foltynowicz, A. (2016). Detection of OH in an atmospheric flame at 1.5 μm using optical frequency comb spectroscopy. Photonics Letters of Poland, 8(4), 110-112
Open this publication in new window or tab >>Detection of OH in an atmospheric flame at 1.5 μm using optical frequency comb spectroscopy
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2016 (English)In: Photonics Letters of Poland, ISSN 2080-2242, E-ISSN 2080-2242, Vol. 8, no 4, p. 110-112Article in journal (Refereed) Published
Abstract [en]

We report broadband detection of OH in a premixed CH4/air flat flame at atmospheric pressure using cavity-enhanced absorption spectroscopy based on an Er:fiber femtosecond laser and a Fourier transform spectrometer. By taking ratios of spectra measured at different heights above the burner we separate twenty OH transitions from the largely overlapping water background. We retrieve from fits to the OH lines the relative variation of OH concentration and flame temperature with a height above the burner and compare them with the 1D simulations of flame structure.

National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-131041 (URN)10.4302/plp.2016.4.07 (DOI)000391182800007 ()
Available from: 2017-02-03 Created: 2017-02-03 Last updated: 2018-06-09Bibliographically approved
Akkerman, V. & Valiev, D. (2016). Effect of gas compression on flame acceleration in obstructed cylindrical tubes. In: : . Paper presented at 2016 Spring Technical Meeting of the Eastern States Section of the Combustion Institute, ESSCI 2016; Princeton University, Princeton, United States, March 13-16, 2016.
Open this publication in new window or tab >>Effect of gas compression on flame acceleration in obstructed cylindrical tubes
2016 (English)Conference paper, Oral presentation only (Other academic)
Abstract [en]

The role of gas compression on the process of extremely fast flame acceleration in obstructed cylindrical tubes is studied analytically and validated by computational simulations. The acceleration leading to a deflagration-to-detonation transition is associated with a powerful jet-flow produced by delayed combustion in spaces between the obstacles. This acceleration mechanism is Reynolds-independent and conceptually laminar, with turbulence playing only a supplementary role. In this particular work, the incompressible formulation [Combust. Flame 157 (2010) 1012], Ref. 15 is extended to account for small but finite initial Mach number up to the first-order terms. While flames accelerate exponentially during the initial stage of propagation, when the compressibility is negligible, with continuous increase in the flame velocity with respect to the tube wall, the flame-generated compression waves subsequently moderate the acceleration process by affecting the flame shape and velocity, as well as the flow driven by the flame. It is demonstrated that the moderation effect is substantial, and as soon as gas compression is relatively small, the present theory is in good quantitative agreement with the computational simulations. The limitations of the incompressible theory are thereby underlined, and a critical blockage ratio for with this acceleration mechanism can be evaluated.

National Category
Other Mechanical Engineering
Identifiers
urn:nbn:se:umu:diva-122452 (URN)
Conference
2016 Spring Technical Meeting of the Eastern States Section of the Combustion Institute, ESSCI 2016; Princeton University, Princeton, United States, March 13-16, 2016
Available from: 2016-06-17 Created: 2016-06-17 Last updated: 2019-06-19Bibliographically approved
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