A Detailed PAH and Soot Model for Complex Fuels in CFD Applications

Abstract

AbstractA model to predict soot evolution during the combustion of complex fuels is presented. On one hand, gas phase, $$\hbox {polycyclic aromatic hydrocarbon (PAH)}$$ polycyclic aromatic hydrocarbon (PAH) and soot chemistry are kept large enough to cover all relevant processes in aero engines. On the other hand, the mechanisms are reduced as far as possible, to enable complex computational fluid dynamics (CFD) combustion simulations. This is important because all species transport equations are solved directly in the $$\hbox {CFD}$$ CFD . Moreover, emphasis is placed on the applicability of the model for a variety of fuels and operating conditions without adjusting it. A kinetic scheme is derived to describe the chemical breakdown of short- and long-chain hydrocarbon fuels and even blends of them. $$\hbox {PAHs}$$ PAHs are the primary soot precursors which are modeled by a sectional approach. The reversibility of the interaction between different $$\hbox {PAH}$$ PAH classes is achieved by the introduction of $$\hbox {PAH}$$ PAH radicals. Soot particles are captured by a detailed sectional approach too, which takes a non-spherical growth of particles into account. In this way the modeling of surface processes is improved. The applicability and validity of the gas phase, $$\hbox {PAH}$$ PAH , and soot model is demonstrated by a large number of shock tube experiments, as well as in atmospheric laminar sooting flames. The presented model achieves excellent results for a wide range of operating conditions and fuels. One set of model constants is used for all simulations and no case-dependent optimization is required.