Abstract:

In numerical simulation of combustion models, solution of the chemical
kinetics is often the most expensive part of the calculation, since
accurate description of kinetic mechanism involves large number of species
and reactions, leading to a large set of coupled ODE's, often too complex
to be considered in their entirety along with a detailed flow simulation.
Hence the need for representing the complex chemical reactions by simple
reduced models, which can retain considerable accuracy while rendering
computational feasibility. Realistically, under different conditions and
at different points in time, different reactions become important, which
has been exploited to develop an adaptive mechanism reduction scheme such
that the reduced reaction model adapts itself to the changing reactor
conditions. A methodology is developed in this work to automatically
construct reduced mechanisms by utilizing mathematical programming
techniques, where the objective is to minimize the dimension of the
system while retaining sufficient accuracy in the prediction of specific
species profiles. The reduced kinetic mechanisms are then analyzed for the
range of conditions over which they retain their predictive capacity.
Those reduced mechanisms are then coupled with the reactive flow
algorithm, by selecting the appropriate mechanism depending on reactor
condition and integrating the corresponding reduced set of ODEs for the
specified valid range. These ideas are demonstrated using the system of
methane combustion in air.

Last modified: Wed May 26 13:11:28 EDT 2004