Numerical modeling of hydrogen hydrothermal combustion in a wall-cooled reactor: Comparison of SCWD-FGM and PaSR models

The supercritical water diluted flamelet generated manifolds (SCWD-FGM) model was newly developed for three-stream hydrothermal combustion systems. It was comprehensively compared with the partially stirred reactor (PaSR) model by modeling a wall-cooled reactor. The results showed that the SCWD-FGM model can predict the mixing of fuel, oxidizer, and cooling water similar to the PaSR model by introducing the dilution variable. The peak temperature along the central axis predicted by the SCWD-FGM model is slightly lower than the PaSR model under adiabatic conditions due to different treatments of turbulent effects and the limited resolution of the SCWD-FGM table. The temperature profiles at 3 mm and 4 mm from the central axis predicted by the two combustion models under non-adiabatic conditions agree with the experiment data. The SCWD-FGM model can predict most species concentrations similarly to the PaSR model except for HO₂ and H₂O₂ radicals. The effect of radiation modeling is similar for the two combustion models since they only affect the radiative source term through the calculated local temperatures. The computational cost for the SCWD-FGM model is 11.2 % of that required for the PaSR model under adiabatic conditions and 14.9 % under non-adiabatic conditions.