Detonation simulations in supersonic flow under circumstances of injection and mixing |
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| Institution: | 1. Science and Technology on Scramjet Laboratory, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073, China;2. Aerodynamics and Flight Mechanics Research Group, University of Southampton, Boldrewood Innovation Campus, Southampton SO16 7QF, United Kingdom;1. Department of Mechanical Engineering, University of Ottawa, 161 Louis Pasteur, Ottawa, ON, K1N6N5, Canada;2. Department of Chemistry and Chemical Engineering, Royal Military College of Canada, 11 Crerar Cres., Kingston, ON K7K7B4, Canada;1. Department of Mechanical and Aerospace Engineering, Center for Advanced Turbomachinery & Energy Research, University of Central Florida, Eng. 1, Rm. 217, Orlando, FL 32816, USA;2. Department of Aerospace Engineering, University of Michigan, Ann Arbor, MI 48109, USA;3. Air Force Research Laboratory, Edwards, CA 93524, USA;1. Purdue University, West Lafayette, IN 47907, United States;2. California Institute of Technology, Pasadena, CA 91125, United States |
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| Abstract: | The unsteady, reactive Navier-Stokes equations with a detailed chemical mechanism of 11 species and 27 steps were employed to simulate the mixing, flame acceleration and deflagration-to-detonation transition (DDT) triggered by transverse jet obstacles. Results show that multiple transverse jet obstacles ejecting into the chamber can be used to activate DDT. But the occurrence of DDT is tremendously difficult in a non-uniform supersonic mixture so that it required several groups of transverse jets with increasing stagnation pressure. The jets introduce flow turbulence and produce oblique and bow shock waves even in an inhomogeneous supersonic mixture. The DDT is enhanced by multiple explosion points that are generated by the intense shock wave focusing of the leading flame front. It is found that the partial detonation front decouples into shock and flame, which is mainly caused by the fuel deficiency, nevertheless the decoupled shock wave is strong enough to reignite the mixture to detonation conditions. The resulting transverse wave leads to further mixing and burning of the downstream non-equilibrium chemical reaction, resulting in a high combustion temperature and intense flow instabilities. Additionally, the longitudinal and transverse gradients of the non-uniform supersonic mixture induce highly dynamic behaviors with sudden propagation speed increase and detonation front instabilities. |
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