Chemistry Tabulation: REDIM Based Implementation to Treat Blended Hydrogen–Methane Combustion Systems

Treatment of the effect of differential/preferential diffusion within manifolds based model reduction concepts, in particular with blended fuels containing hydrogen, represents a challenging problem. Recently these have gained special attention both from implementation as well as from theoretical standpoints. The problem is difficult for reduced modeling because the diffusion complicates the system solution properties in the state space and requires the description of the diffusion term in reduced variables. The present study uses reaction diffusion manifolds (REDIM) to show the capability of the method to accurately reproduce the effects of differential diffusion. In order to keep the framework simple and demonstrate the problem, a premixed flat flame configuration is considered. Additional focus is made on methane blended with hydrogen combustion systems. This is because complex fuel mixtures having significantly different combustion characteristics represent an attractive system for sustainable combustion. The properties of system solutions of detailed and reduced computations are presented, discussed and compared. In the case of a constant parametrization the effect of different projection strategies are studied and modification to the implementation concept is proposed. The parametrization invariance of the implementation scheme is achieved. It is shown that the accuracy of the physical properties computed in both generalized coordinates as well as a modified constant parametrization projection remains high, as the composition of the system changes due to hydrogen dilution.