This study presents a new three-step global chemical mechanism for n-decane/air combustion, specifically optimized for efficient simulation of oblique detonation waves (ODWs). The parameters in the global mechanism were specially formulated to enable predictions of essential features in ODWs, including ignition delays, heat release distribution, and detonation velocity with substantially reduced computational cost while preserving fidelity. Comprehensive validations are conducted through extensive numerical simulations, supported by direct comparisons with experimental shock tube data and a skeletal mechanism (Skel40). The proposed mechanism was found to demonstrate predictive robustness across a wide range of combustor conditions, spanning initial temperatures from 600 to 1600 K, pressures from 10 to 1000 kPa, and equivalence ratios from 0.5 to 1.6. As demonstrated in two-dimensional simulations of ODWs, the proposed three-step mechanism predicts key features consistent with those from Skel40 but with a 56-fold improvement in computational efficiency. This new capability provides a reliable and convenient alternative for system-level detonation modeling.
