Modelling of the correlation between velocity and reactive scalar gradients in turbulent premixed flames based on DNS data |
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| Authors: | Arnaud Mura Kazuya Tsuboi Tatsuya Hasegawa |
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| Institution: | 1. Laboratoire de Combustion et de Détonique , ENSMA , UPR 9028 CNRS, Poitiers, France;2. EcoTopia Science Institute, Nagoya University , Nagoya, Japan |
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| Abstract: | The interaction between turbulence and reactive scalar fields is discussed for the wrinkled flamelets regime of turbulent premixed combustion. Emphasis is placed on the effects associated with the turbulent straining term. In the regime of turbulent combustion under consideration, which corresponds to Karlovitz and Damköhler numbers such that Ka < 1 and Da > 1, a clear and simple formulation is proposed to explain and to model the influence of the correlation between velocity and reactive scalar gradients. This formulation is based on the conservative variables budget across one-dimensional premixed laminar flamelets. The analysis firmly confirms the dependence on both the Damköhler number and the expansion factor, a feature already foreseen in recent studies. Nevertheless, in contrast with previous work, (i) the scaling arguments used in the present contribution are different from those used in other recent proposals, and (ii) the proposed closures are not only deduced from dimensional arguments but also from the consideration of conservative variable budgets across laminar flamelets. The resulting functional dependence on the expansion factor is found to be influenced by the underlying one-dimensional flamelet representation and two possible closures are put forward to take this dependence into account. (iii) The two closures do not exhibit a proportionality to the mean scalar dissipation rate   | |
| Keywords: | reactive scalar dissipation rate turbulent premixed combustion wrinkled flamelet regime |
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