Numerical study on the effects of obstacle shape and thickness on deflagration-to-detonation transition in hydrogen–air mixtures with a transverse concentration gradient
This study explores the deflagration-to-detonation transition (DDT) in a 30 % hydrogen–air mixture with a transverse concentration gradient through numerical simulation. The study aims to analyze the impact of obstacle shapes and thicknesses on DDT mechanisms in the inhomogeneous mixture. The combus...
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Elsevier
2025-02-01
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| Series: | Case Studies in Thermal Engineering |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2214157X2401757X |
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| author | Mohammad Hossein Shamsaddin Saeid Chang Bo Oh Chi Young Lee |
| author_facet | Mohammad Hossein Shamsaddin Saeid Chang Bo Oh Chi Young Lee |
| author_sort | Mohammad Hossein Shamsaddin Saeid |
| collection | DOAJ |
| description | This study explores the deflagration-to-detonation transition (DDT) in a 30 % hydrogen–air mixture with a transverse concentration gradient through numerical simulation. The study aims to analyze the impact of obstacle shapes and thicknesses on DDT mechanisms in the inhomogeneous mixture. The combustion chamber, a rectangular channel with both ends closed, contains seven obstacles with a blockage ratio (BR) of 0.6. The numerical results demonstrate significant variations in flame and flow dynamics depending on whether rectangular or semicircular obstacles are used. Rectangular obstacles cause the flame to collide more directly with their edges, producing stronger, more concentrated vortices and a jet-like flow that accelerates the flame front more effectively. Two primary detonation initiation mechanisms are identified through the comparison of these obstacle shapes: (1) collision of the shock wave reflected from the obstacle with the flame, and (2) focusing of pressure waves near the flame front. Furthermore, semicircular obstacles facilitate a more controlled DDT process compared to rectangular ones. This control is achieved because the round shape is less favorable for flame stretching or convolution, producing smaller recirculation zones. Semicircular obstacles lead to smoother flame interactions, generating less intense vortices and resulting in slower flame propagation and delayed DDT, thereby lowering the risk of detonation occurring and reducing potential economic losses. Varying the thickness of rectangular obstacles emphasizes the significance of shock–flame interactions and the role of the Mach stem formed near the lower wall in DDT mechanisms. |
| format | Article |
| id | doaj-art-f67929b2cd734930aeabc976458fbd75 |
| institution | Kabale University |
| issn | 2214-157X |
| language | English |
| publishDate | 2025-02-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Case Studies in Thermal Engineering |
| spelling | doaj-art-f67929b2cd734930aeabc976458fbd752025-02-02T05:27:17ZengElsevierCase Studies in Thermal Engineering2214-157X2025-02-0166105726Numerical study on the effects of obstacle shape and thickness on deflagration-to-detonation transition in hydrogen–air mixtures with a transverse concentration gradientMohammad Hossein Shamsaddin Saeid0Chang Bo Oh1Chi Young Lee2Department of Safety Engineering, Pukyong National University, 45 Yongso-ro, Nam-gu, Busan, 48513, Republic of KoreaDepartment of Safety Engineering, Pukyong National University, 45 Yongso-ro, Nam-gu, Busan, 48513, Republic of Korea; Corresponding author.Department of Fire Protection Engineering, Pukyong National University, 45 Yongso-ro, Nam-gu, Busan, 48513, Republic of KoreaThis study explores the deflagration-to-detonation transition (DDT) in a 30 % hydrogen–air mixture with a transverse concentration gradient through numerical simulation. The study aims to analyze the impact of obstacle shapes and thicknesses on DDT mechanisms in the inhomogeneous mixture. The combustion chamber, a rectangular channel with both ends closed, contains seven obstacles with a blockage ratio (BR) of 0.6. The numerical results demonstrate significant variations in flame and flow dynamics depending on whether rectangular or semicircular obstacles are used. Rectangular obstacles cause the flame to collide more directly with their edges, producing stronger, more concentrated vortices and a jet-like flow that accelerates the flame front more effectively. Two primary detonation initiation mechanisms are identified through the comparison of these obstacle shapes: (1) collision of the shock wave reflected from the obstacle with the flame, and (2) focusing of pressure waves near the flame front. Furthermore, semicircular obstacles facilitate a more controlled DDT process compared to rectangular ones. This control is achieved because the round shape is less favorable for flame stretching or convolution, producing smaller recirculation zones. Semicircular obstacles lead to smoother flame interactions, generating less intense vortices and resulting in slower flame propagation and delayed DDT, thereby lowering the risk of detonation occurring and reducing potential economic losses. Varying the thickness of rectangular obstacles emphasizes the significance of shock–flame interactions and the role of the Mach stem formed near the lower wall in DDT mechanisms.http://www.sciencedirect.com/science/article/pii/S2214157X2401757XMixture inhomogeneityDeflagrationDetonationObstacle shapesObstacle thickness |
| spellingShingle | Mohammad Hossein Shamsaddin Saeid Chang Bo Oh Chi Young Lee Numerical study on the effects of obstacle shape and thickness on deflagration-to-detonation transition in hydrogen–air mixtures with a transverse concentration gradient Case Studies in Thermal Engineering Mixture inhomogeneity Deflagration Detonation Obstacle shapes Obstacle thickness |
| title | Numerical study on the effects of obstacle shape and thickness on deflagration-to-detonation transition in hydrogen–air mixtures with a transverse concentration gradient |
| title_full | Numerical study on the effects of obstacle shape and thickness on deflagration-to-detonation transition in hydrogen–air mixtures with a transverse concentration gradient |
| title_fullStr | Numerical study on the effects of obstacle shape and thickness on deflagration-to-detonation transition in hydrogen–air mixtures with a transverse concentration gradient |
| title_full_unstemmed | Numerical study on the effects of obstacle shape and thickness on deflagration-to-detonation transition in hydrogen–air mixtures with a transverse concentration gradient |
| title_short | Numerical study on the effects of obstacle shape and thickness on deflagration-to-detonation transition in hydrogen–air mixtures with a transverse concentration gradient |
| title_sort | numerical study on the effects of obstacle shape and thickness on deflagration to detonation transition in hydrogen air mixtures with a transverse concentration gradient |
| topic | Mixture inhomogeneity Deflagration Detonation Obstacle shapes Obstacle thickness |
| url | http://www.sciencedirect.com/science/article/pii/S2214157X2401757X |
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