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Zone conditional assessment of flame-generated turbulence with DNS database of a turbulent premixed flame |
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| Authors: | Yong-Hoon Im Shinnosuke Nishiki |
| Affiliation: | a Department of Mechanical Engineering, Pohang University of Science & Technology, Pohang, Kyungbuk, South Korea 790-784 b Department of Mechanical Engineering, Nagaoka University of Technology, Kamitomioka, Nagaoka, Japan c Center for Integrated Research in Science and Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Japan |
| Abstract: | Zone conditional two-fluid equations are derived and validated against a DNS database for a turbulent premixed flame. The conditional statistics of major flow variables are investigated to understand the mechanism of flame-generated turbulence. The flow field in the burned region shows substantially increased, highly anisotropic turbulence to conserve mass through a flamelet surface. The transverse component may be larger than the axial component for a distributed pdf of the flamelet orientation angle in the middle of the flame brush. The opposite occurs due to redistribution of turbulent kinetic energy and flamelet orientation mostly normal with respect to the mean flow at the end of the flame brush. The major source or sink terms of turbulent kinetic energy are the interfacial transfer by the mean reaction rate and the work terms induced by fluctuating pressure and velocity on the flame surface. Ad hoc modeling of some interfacial terms may be required for further application of the two-fluid model for modeling turbulence in turbulent premixed combustion simulations. |
| Keywords: | Flame-generated turbulence Zone conditional averaging Turbulent premixed flame Two-fluid model Direct numerical simulation |
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