Numerical studies on autoignition and detonation development from a hot spot in hydrogen/air mixtures |
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Authors: | Yuan Gao Peng Dai |
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Affiliation: | 1. SKLTCS, CAPT, College of Engineering, Peking University, Beijing, People’s Republic of China;2. Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology, Shenzhen, People’s Republic of China |
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Abstract: | Detonation development inside spark ignition engines can result in the so called super-knock with extremely high pressure oscillation above 200?atm. In this study, numerical simulations of autoignitive reaction front propagation in hydrogen/air mixtures are conducted and the detonation development regime is investigated. A hot spot with linear temperature distribution is used to induce autoignitive reaction front propagation. With the change of temperature gradient or hot spot size, three typical autoignition reaction front modes are identified: supersonic reaction front; detonation development and subsonic reaction front. The effects of initial pressure, initial temperature, fuel type and equivalence ratio on detonation development regime are examined. It is found that the detonation development regime strongly depends on mixture composition (fuel and equivalence ratio) and thermal conditions (initial pressure and temperature). Therefore, to achieve the quantitative prediction of super-knock in engines, we need use the detonation development regime for specific fuel at specific initial temperature, initial pressure, and equivalence ratio. |
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Keywords: | detonation development autoignitive reaction front hydrogen/air temperature gradient |
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