NASA’s Jet Propulsion Laboratory, Pasadena, California
Combustion of realistic fuels is described by thousands of reactions involving thousands of species. Coupling these detailed chemical mechanisms with turbulence simulations is completely impractical because there is no computer powerful enough to solve the resulting equations.
A reduced-kinetics mechanism has been developed that uses only a few important species to duplicate the detailed mechanism at much lower computational cost. The compact reduced-kinetics mechanism has been developed for n-C16H34 oxidation that is based on a local full similarity of the detailed mechanism. The reduced mechanism employs only 20 light species and since the light-species reaction rates are more accurately known than those for heavy species, the present reduced mechanism has a smaller relative error than a reduced mechanism employing reactions involving heavy species.
The model was exercised in the context of a fixed-mass, constant-pressure reactor, and results were obtained over the entire range of equivalence-ratio validity of the detailed mechanism at the high pressures encountered in diesel, gas-turbine, and HCCI (homogeneous charge compression ignition) engines, and at both cold-ignition and hot-ignition temperatures. The results uniformly show excellent accuracy on the temporal evolution of the temperature, the major species mass fraction, and the OH mass fraction when compared to those of the detailed mechanism.
One advantage of the developed reduced kinetics is that it consists of the same 20 species for n-C7H16, n-C10H22, n-C12H26, n-C16H34, and i-C8H18, making it easy to use a reduced model for mixtures of species composing a practical fuel.