Laminar Combustion and Explosive Characteristics of Ternary Premixed Fuels at High Pressure

This study systematically investigated the laminar burning and explosive characteristics of an ethanol-hydrogen-methane ternary premixed fuel at high pressure. Experiments were conducted in a constant-volume combustion system at initial temperature of 400 K, initial pressure (p₀) ranging from 0.1 to 0.4 MPa, equivalence ratio (ϕ) between 0.7 and 1.4, and the volume fraction ethanol of 20%, 50%, and 80%. The results show that the strongest combustion instability occurs at an equivalence ratio of 1.1, while the instability intensity increasing with higher ethanol content and elevated pressure. The laminar burning velocity (LBV) decreases with increasing pressure and ethanol concentration, deviating by less than 7% from kinetic simulation results. Regarding explosion characteristics, the maximum explosion pressure p_max exhibits a linear correlation with the initial pressure, and the slope of this relation increases with a higher ethanol ratios. The maximum rate of pressure rise peaks at ϕ=1.1, reaching a maximum value of 188 MPa/s, which corresponds to a deflagration index of 23.66 MPa·m/s, indicating a relatively safe level. The optimal combustion ranges for different ethanol blending ratios are as follows: ϕ is 1.2–1.3, p₀ is 0.1–0.3 MPa at 20% ethanol; ϕ is 1.1–1.2 and p₀≈0.3 MPa at 50% ethanol; ϕ is 1.0–1.1 and p₀≈0.1 MPa at 80% ethanol. Kinetic analysis further reveals that reaction R1 serves as the dominant chain-branching step, playing a key role in enhancing the burning rate. The simulation accurately captures the evolution trends of radical species, validating the rationality of the reaction kinetic model. This study reveals the synergistic effects of ethanol proportion and pressure on the combustion and explosion behavior of ternary fuels, providing valuable references for the design of efficient clean fuels and the optimization of combustion chambers.