A novel global chemical reaction mechanism for large-scale hydrogen detonation simulation

Abstract

Conventional modeling strategies for large-scale detonation simulations suffer from a critical trade-off: detailed chemical mechanisms involve excessive computational costs, while typical single-step schemes lack sufficient predictive accuracy. To resolve this issue, this study proposes a novel single-step chemical reaction mechanism to simulate hydrogen-fueled detonation wave propagation in large-scale geometric configurations. Due to the substantial discrepancy in equilibrium temperature between the conventional irreversible single-step reaction mechanism and the detailed mechanism, the central concept in developing the new mechanism is to calibrate the equilibrium temperature of the single-step mechanism. The Nelder-Mead simplex optimization algorithm is employed to fine-tune the thermodynamic parameters of the single-step reaction mechanism ensuring agreement with the equilibrium temperature predicted by the detailed mechanism across a broad range of operational conditions. To validate the predictive capability of the new single-step mechanism in detonation wave propagation speed and peak overpressure, three distinct test cases were simulated using an OpenFOAM-type solver. The results demonstrate that the computational accuracy of the new single-step mechanism is comparable to that of the detail model (Keromnes'11-component, 24-reaction mechanism, hereinafter referred to as the KS mechanism in this study) when comparing detonation wave velocities and overpressure peaks. Furthermore, the total simulation time of the new single-step mechanism in this study was only 1.25% of that of the KS mechanism, and the new single-step mechanism exhibits lower sensitivity to grid resolution compared to the detailed mechanism. These findings indicate that the proposed mechanism is particularly well-suited for large-scale simulations of hydrogen fuel detonation.