Impact of non-ideal corrections to equation of state, thermodynamics, and chemical kinetics on one-dimensional freely propagating flame structure

摘要

In the current generation industrial combustion devices for propulsion and energy generation, a common trend of increase in operating pressure can be observed. Primary motivation behind this increase in operating pressure is improvement in efficiency and a compact combustion chamber. At these high-pressure conditions observed in combustion chambers, an ideal gas equation of state is no longer valid. Moreover, at operating conditions similar and above the critical point of the fuel-air mixture the discrete interface between gas and liquid phase is no longer observed and instead a more diffused interface is seen. Thermodynamic and transport properties undergo a sharp but continuous change around this diffused interface, resulting in a large deviation from the ideal gas predictions. In the present study, the impact of departure from the ideal gas is studied on a canonical freely propagating one-dimensional premixed flame. A cubic equation of state (EOS) namely the Soave-Redlich-Kwong is used as the constitutive relationship and is used to compute other thermodynamic information such as specific heat at constant pressure, Cp. Chemical kinetics are also modified to accommodate chemical activity coefficients instead of molar concentrations. Impact of all these non-ideal modifications on chemical kinetics, thermodynamics, on 1-D premixed flame structure will be investigated in this study. Additionally, flame structure corresponding to different fuels namely hydrogen and methane are also highlighted in the context of non-ideal modifications to thermodynamics.