Applications of lagrangian models to turbulent combustion

✍ Scribed by R. Borghi; M. Gonzalez

• Publisher: Elsevier Science
• Year: 1986
• Tongue: English
• Weight: 727 KB
• Volume: 63
• Category: Article
• ISSN: 0010-2180
• DOI: 10.1016/0010-2180(86)90124-0

✦ Synopsis

The work presented here concerns the application of Lagrangian models of turbulent combustion in order to take into account the broad spectrum of time scales existing in turbulence.

After a brief review of the history of Lagrangian models and their principles, a first model is proposed where the combustion is assumed to be very sudden and a distribution of time scales of the turbulence is to be given. For the sake of simplicity, the application is restricted to the case of a well-stirred reactor. With the assumption of unity Lewis numbers, it is demonstrated that all interesting quantities can be computed as functions of (i) the p.d.f, of an inert injected similarly to the reactant and having the same diffusivity, (ii) a chemical quantity related to an ignition delay, and (iii) a turbulent time scale distribution.

As a second model we have converted the model of Meyers and O'Brien for the joint fluctuations of a reactive species and its spatial gradient into a Lagrangian model for a well-stirred reactor. That gives a Lagrangian model with a single time scale of the turbulence which depends upon the reaction. The result of such a model is the skeleton of the joint p.d.f, for the concentration of a reactive species and its spatial gradient. The modification of that p.d.f, due to the turbulence Reynolds number and the reaction term is examined.