Non-gray radiation model optimized for hydrogen flames

This study investigates the accuracy and efficiency of a non-gray radiation model for pure hydrogen combustion. A precomputed table framework with a quadrature transformation strategy is developed for the Rank-Correlated Full-Spectrum k -distribution (RCFSK) method to improve the performance at low quadrature orders. RCFSK predictions are compared against Line-by-Line (LBL) benchmarks in two artificial test cases, representative of furnace-like flame conditions, and a Sandia plume. The accuracy of the generated tables is further examined with spectrally varying wall emissivity. Results show that RCFSK consistently provides better accuracy than the Weighted-Sum-of-Gray-Gases (WSGG) model at comparable numbers of radiative transfer equations (RTE) solutions, while requiring less than one-third of the computational cost. The peak normalized errors remain below 15% for the radiative source term and below 7% for wall heat flux, with significantly lower average values. For the spectral wall emission cases, the source term is accurately captured using Planck mean emissivity and absorptivity evaluated at the wall temperature. Finally, application to a Sandia plume through a decoupled CFD solution demonstrates substantially improved accuracy relative to WSGG. • RCFSK precomputed table was developed for efficient H 2 O radiation calculations. • Accuracy was tested on multiple cases, including the Sandia flame. • Method consumes less than one-third of WSGG time while achieving superior accuracy.