Large eddy simulation of mean and oscillating flow in a side-dump ramjet combustor |
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| Authors: | A Roux LYM Gicquel Y Sommerer TJ Poinsot |
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| Affiliation: | 1. CERFACS, CFD team, 42 Av. G. Coriolis, 31057 Toulouse Cedex, France;2. Institut de Mécanique des Fluides de Toulouse, Avenue C. Soula, 31400 Toulouse, France;1. School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, China;2. School of Mechanical and Aerospace Engineering, College of Engineering, Nanyang Technological University, 639798, Singapore;3. School of Aeronautics and Astronautics, Dalian University of Technology, Dalian 116024, China;1. Science and Technology on Scramjet Laboratory, National University of Defense Technology, Changsha 410073, China;2. Academy of Equipment, Huairou, Beijing 101416, China;1. School of Mechanical and Automotive Engineering, Zhejiang University of Science and Technology, Hangzhou City, Liuhe Road, Zhejiang, 310023, China;2. School of Mechanical and Aerospace Engineering, College of Engineering, Nanyang Technological University, Singapore, 639798, Republic of Singapore;3. College of Mechanical and Vehicle Engineering, Hunan University, 410082, Changsa City, Hunan Province, China;4. School of Aerospace Engineering, Beijing Institute of Technology, 100081, Beijing, China;1. Department of Mechanical Engineering, College of Engineering, University of Canterbury, Private Bag 4800, Christchurch, 8140, New Zealand;2. School of Aerospace Engineering, Beijing Institute of Technology, Beijing, 100083, China;1. School of Mechanical Aerospace Engineering, College of Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore;2. Key Laboratory for Power Machinery and Engineering of MOE, Shanghai Jiao Tong University, Shanghai 200240, PR China |
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| Abstract: | Ramjet flows are very sensitive to combustion instabilities that are difficult to predict using numerical simulations. This paper describes compressible large eddy simulation on unstructured grids used to investigate nonreacting and reacting flows in a simplified twin-inlet ramjet combustor. The reacting flow is compared to experimental results published by ONERA in terms of mean fields. Simulations show a specific flow topology controlled by the impingement of the two air jets issuing from the twin air inlets and by multiple complex recirculation zones. In a second part, all unsteady modes appearing in the reacting LES are analyzed using spectral maps and POD (proper orthogonal decomposition) tools. A Helmholtz solver also computes the frequencies and structures of all acoustic modes in the ramjet. Pure longitudinal, transverse and combined modes are identified by all three diagnostics. In addition, a mode-by-mode analysis of the Rayleigh criterion is presented thanks to POD. This method shows that the most intense structure (at 3750 Hz) is the first transverse acoustic mode of the combustor chamber and the Rayleigh criterion obtained with POD illustrates how this transverse mode couples with unsteady combustion. |
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