Macrokinetic Behavior of Hydrogen Combustion under High Pressure with Turbulence and Thermal Inhomogeneity

This study investigates how turbulence intensity and temperature gradients affect the macroscopic kinetics of hydrogen-air combustion at supercritical pressures from 10 to 20 MPa. A series of high-precision experiments was conducted in a custom-designed high-pressure combustion reactor with a controllable thermal field and adjustable turbulent-flow generation. The induction period for spontaneous ignition was measured under various turbulence regimes and temperature distributions. Increasing turbulence intensity from 0% to 20% reduced the induction period from 0.71 s to 0.39 s, and imposing a linear temperature gradient of 300 K over 15 cm further decreased it to 0.26 s. The maximum radical concentrations of H and OH were 3.5×10–⁴ and 3.9×10–⁴ mol/mol at 20 MPa and 1000 K, indicating enhanced chain-reaction activity in locally overheated regions. Numerical simulations using a modified global kinetic model deviated by less than 8% from the experimental data. The findings support the development of improved macrokinetic models suitable for engineering applications involving hydrogen combustion at high pressures with complex thermal and flow fields.