Computational Study of Premixed Flame Propagation in Micro-Channels with Nonslip Walls: Effect of Wall Temperature
This investigation evaluates the propagation of premixed flames in narrow channels with isothermal walls. The study is based on the numerical solution of the set of fully-compressible, reacting flow equations that includes viscosity, diffusion, thermal conduction and Arrhenius chemical kinetics. Spe...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-01-01
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| Series: | Fluids |
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| Online Access: | https://www.mdpi.com/2311-5521/6/1/36 |
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| author | Orlando J. Ugarte V’yacheslav Akkerman |
| author_facet | Orlando J. Ugarte V’yacheslav Akkerman |
| author_sort | Orlando J. Ugarte |
| collection | DOAJ |
| description | This investigation evaluates the propagation of premixed flames in narrow channels with isothermal walls. The study is based on the numerical solution of the set of fully-compressible, reacting flow equations that includes viscosity, diffusion, thermal conduction and Arrhenius chemical kinetics. Specifically, channels and pipes with one extreme open and one extreme closed are considered such that a flame is sparked at the closed extreme and propagates towards the open one. The isothermal channel walls are kept at multiple constant temperatures in the range from <inline-formula><math display="inline"><semantics><mrow><msub><mi>T</mi><mi>w</mi></msub><mo>=</mo><mn>300</mn><mo> </mo><mi mathvariant="normal">K</mi></mrow></semantics></math></inline-formula> to <inline-formula><math display="inline"><semantics><mrow><mn>1200</mn><mo> </mo><mi mathvariant="normal">K</mi></mrow></semantics></math></inline-formula>. The impact of these isothermal walls on the flame dynamics is studied for multiple radii of the channel (<inline-formula><math display="inline"><semantics><mi>R</mi></semantics></math></inline-formula>) and for various thermal expansion ratios (<inline-formula><math display="inline"><semantics><mi mathvariant="sans-serif">Θ</mi></semantics></math></inline-formula>), which approximate the thermal behavior of different fuel mixtures in the system. The flame dynamics in isothermal channels is also compared to that with adiabatic walls, which were previously found to produce exponential flame acceleration at the initial stage of the burning process. The results show that the heat losses at the walls prevent strong acceleration and lead to much slower flame propagation in isothermal channels as compared to adiabatic ones. Four distinctive regimes of premixed burning in isothermal channels have been identified in the <inline-formula><math display="inline"><semantics><mrow><mi mathvariant="sans-serif">Θ</mi><mo>−</mo><msub><mi>T</mi><mi>w</mi></msub><mo>−</mo><mi>R</mi></mrow></semantics></math></inline-formula> space: (i) flame extinction; (ii) linear flame acceleration; (iii) steady or near-steady flame propagation; and (iv) flame oscillations. The physical processes in each of these regimes are discussed, and the corresponding regime diagrams are presented. |
| first_indexed | 2024-03-09T05:11:59Z |
| format | Article |
| id | doaj.art-689bb03105bd4640b72ad5c03eea4652 |
| institution | Directory Open Access Journal |
| issn | 2311-5521 |
| language | English |
| last_indexed | 2024-03-09T05:11:59Z |
| publishDate | 2021-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Fluids |
| spelling | doaj.art-689bb03105bd4640b72ad5c03eea46522023-12-03T12:48:24ZengMDPI AGFluids2311-55212021-01-01613610.3390/fluids6010036Computational Study of Premixed Flame Propagation in Micro-Channels with Nonslip Walls: Effect of Wall TemperatureOrlando J. Ugarte0V’yacheslav Akkerman1Center for Innovation in Gas Research and Utilization (CIGRU), Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV 26506-6106, USACenter for Innovation in Gas Research and Utilization (CIGRU), Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV 26506-6106, USAThis investigation evaluates the propagation of premixed flames in narrow channels with isothermal walls. The study is based on the numerical solution of the set of fully-compressible, reacting flow equations that includes viscosity, diffusion, thermal conduction and Arrhenius chemical kinetics. Specifically, channels and pipes with one extreme open and one extreme closed are considered such that a flame is sparked at the closed extreme and propagates towards the open one. The isothermal channel walls are kept at multiple constant temperatures in the range from <inline-formula><math display="inline"><semantics><mrow><msub><mi>T</mi><mi>w</mi></msub><mo>=</mo><mn>300</mn><mo> </mo><mi mathvariant="normal">K</mi></mrow></semantics></math></inline-formula> to <inline-formula><math display="inline"><semantics><mrow><mn>1200</mn><mo> </mo><mi mathvariant="normal">K</mi></mrow></semantics></math></inline-formula>. The impact of these isothermal walls on the flame dynamics is studied for multiple radii of the channel (<inline-formula><math display="inline"><semantics><mi>R</mi></semantics></math></inline-formula>) and for various thermal expansion ratios (<inline-formula><math display="inline"><semantics><mi mathvariant="sans-serif">Θ</mi></semantics></math></inline-formula>), which approximate the thermal behavior of different fuel mixtures in the system. The flame dynamics in isothermal channels is also compared to that with adiabatic walls, which were previously found to produce exponential flame acceleration at the initial stage of the burning process. The results show that the heat losses at the walls prevent strong acceleration and lead to much slower flame propagation in isothermal channels as compared to adiabatic ones. Four distinctive regimes of premixed burning in isothermal channels have been identified in the <inline-formula><math display="inline"><semantics><mrow><mi mathvariant="sans-serif">Θ</mi><mo>−</mo><msub><mi>T</mi><mi>w</mi></msub><mo>−</mo><mi>R</mi></mrow></semantics></math></inline-formula> space: (i) flame extinction; (ii) linear flame acceleration; (iii) steady or near-steady flame propagation; and (iv) flame oscillations. The physical processes in each of these regimes are discussed, and the corresponding regime diagrams are presented.https://www.mdpi.com/2311-5521/6/1/36premixed flamesisothermal and adiabatic boundary conditionsnarrow channelscomputational simulations |
| spellingShingle | Orlando J. Ugarte V’yacheslav Akkerman Computational Study of Premixed Flame Propagation in Micro-Channels with Nonslip Walls: Effect of Wall Temperature Fluids premixed flames isothermal and adiabatic boundary conditions narrow channels computational simulations |
| title | Computational Study of Premixed Flame Propagation in Micro-Channels with Nonslip Walls: Effect of Wall Temperature |
| title_full | Computational Study of Premixed Flame Propagation in Micro-Channels with Nonslip Walls: Effect of Wall Temperature |
| title_fullStr | Computational Study of Premixed Flame Propagation in Micro-Channels with Nonslip Walls: Effect of Wall Temperature |
| title_full_unstemmed | Computational Study of Premixed Flame Propagation in Micro-Channels with Nonslip Walls: Effect of Wall Temperature |
| title_short | Computational Study of Premixed Flame Propagation in Micro-Channels with Nonslip Walls: Effect of Wall Temperature |
| title_sort | computational study of premixed flame propagation in micro channels with nonslip walls effect of wall temperature |
| topic | premixed flames isothermal and adiabatic boundary conditions narrow channels computational simulations |
| url | https://www.mdpi.com/2311-5521/6/1/36 |
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