Flame acceleration and transition to detonation in a pre-/main- chamber combustion system
Numerical simulations are performed to study the mechanism of deflagration to detonation transition (DDT) in a pre-/main- chamber combustion system. The fully compressible Navier-Stokes equations, coupled with a chemical-diffusive model in a stoichiometric ethylene-oxygen mixture, are solved with a...
| Main Authors: | , , , |
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| Format: | Journal article |
| Language: | English |
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AIP Publishing
2022
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| _version_ | 1797108584013627392 |
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| author | Lai, S Xu, C Davy, M Fang, X |
| author_facet | Lai, S Xu, C Davy, M Fang, X |
| author_sort | Lai, S |
| collection | OXFORD |
| description | Numerical simulations are performed to study the mechanism of deflagration to detonation transition (DDT) in a pre-/main- chamber combustion system. The fully compressible Navier-Stokes equations, coupled with a chemical-diffusive model in a stoichiometric ethylene-oxygen mixture, are solved with a high-order numerical algorithm on a dynamically adapting mesh. The two-dimensional simulation shows that a laminar flame grows in the pre-chamber and then develops into a jet flame as it passes through the orifice. A strong shock forms immediately ahead of the flame, reflecting off the walls, and interacting with the flame front. The shock-flame interactions are crucial for the development of flame instabilities, which trigger the subsequent turbulent flame development. The DDT arises due to an energy-focusing mechanism, where multiple shocks collide at the flame front. A chemical explosive mode analysis (CEMA) criteria is developed to study the DDT ignition mode. Preliminary one-dimensional computations for a laminar propagating flame, a fast flame deflagration, and a Chapman-Jouguet detonation are conducted to demonstrate the validity of CEMA on the chemical-diffusive model, as well as to determine the proper conditioning value for CEMA diagnostic. The two-dimensional analysis with CEMA indicates that the DDT initiated by the energy focusing mechanism can form a strong thermal expansion region that features large positive eigenvalues for the chemical explosive mode and dominance of the local autoignition mode. Thus, the CEMA criterion proposed in this study provides a robust diagnostic for identifying autoignition-supported DDT of which emergence of excessive local autoignition mode is found to be a precursor. |
| first_indexed | 2024-03-07T07:30:57Z |
| format | Journal article |
| id | oxford-uuid:ca31f7d3-4c60-4f6a-84f9-e530f291bd03 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T07:30:57Z |
| publishDate | 2022 |
| publisher | AIP Publishing |
| record_format | dspace |
| spelling | oxford-uuid:ca31f7d3-4c60-4f6a-84f9-e530f291bd032023-01-12T10:55:18ZFlame acceleration and transition to detonation in a pre-/main- chamber combustion systemJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:ca31f7d3-4c60-4f6a-84f9-e530f291bd03EnglishSymplectic ElementsAIP Publishing2022Lai, SXu, CDavy, MFang, XNumerical simulations are performed to study the mechanism of deflagration to detonation transition (DDT) in a pre-/main- chamber combustion system. The fully compressible Navier-Stokes equations, coupled with a chemical-diffusive model in a stoichiometric ethylene-oxygen mixture, are solved with a high-order numerical algorithm on a dynamically adapting mesh. The two-dimensional simulation shows that a laminar flame grows in the pre-chamber and then develops into a jet flame as it passes through the orifice. A strong shock forms immediately ahead of the flame, reflecting off the walls, and interacting with the flame front. The shock-flame interactions are crucial for the development of flame instabilities, which trigger the subsequent turbulent flame development. The DDT arises due to an energy-focusing mechanism, where multiple shocks collide at the flame front. A chemical explosive mode analysis (CEMA) criteria is developed to study the DDT ignition mode. Preliminary one-dimensional computations for a laminar propagating flame, a fast flame deflagration, and a Chapman-Jouguet detonation are conducted to demonstrate the validity of CEMA on the chemical-diffusive model, as well as to determine the proper conditioning value for CEMA diagnostic. The two-dimensional analysis with CEMA indicates that the DDT initiated by the energy focusing mechanism can form a strong thermal expansion region that features large positive eigenvalues for the chemical explosive mode and dominance of the local autoignition mode. Thus, the CEMA criterion proposed in this study provides a robust diagnostic for identifying autoignition-supported DDT of which emergence of excessive local autoignition mode is found to be a precursor. |
| spellingShingle | Lai, S Xu, C Davy, M Fang, X Flame acceleration and transition to detonation in a pre-/main- chamber combustion system |
| title | Flame acceleration and transition to detonation in a pre-/main- chamber combustion system |
| title_full | Flame acceleration and transition to detonation in a pre-/main- chamber combustion system |
| title_fullStr | Flame acceleration and transition to detonation in a pre-/main- chamber combustion system |
| title_full_unstemmed | Flame acceleration and transition to detonation in a pre-/main- chamber combustion system |
| title_short | Flame acceleration and transition to detonation in a pre-/main- chamber combustion system |
| title_sort | flame acceleration and transition to detonation in a pre main chamber combustion system |
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