Investigation on n-decane-hydrogen laminar combustion characteristics using the constant volume combustion method

Abstract

The laminar burning velocity of n-decane (an aviation kerosene surrogate) blended with hydrogen is studied using experimental and numerical analysis at the initial conditions of 470 K and 1, 2, and 4 bar over the equivalence ratios of 0.7–1.3 and hydrogen addition ratios of 0 %, 10 %, 20 %, 30 %, 40 %, and 50 %. The burning velocity is investigated using the constant volume method of the spherically expanding flame method. Here, burning velocity at elevated pressure and temperature conditions close to engine-relevant conditions have been established. Thus, using the experimental data at 470 K and 4 bar, burning velocities at the unburnt temperatures of up to 612 K and pressures of up to 11.02 bar are obtained. Also, Polimi and JetSurF2.0 mechanisms were used to simulate the burning velocities and they agreed well with the experimental data. However, as the hydrogen addition increased, especially when the hydrogen addition was 40 % there was a significant deviation between the experiment and the simulation results. The chemical reaction analysis of n-decane-hydrogen shows the flame speed is significantly driven by H+O2⇔O+OH, CO+OH⇔CO2+H, CH3+H(+M)⇔CH4(+M), and H+OH+M⇔H2O+M at the various initial conditions. However, H+O2⇔O+OH produces more OH, H, and O radicals that accelerate the combustion chemical reaction rate of n-decane-hydrogen. The reaction pathways show that the decomposition of n-decane is mainly controlled by the OH and H radicals. This study's results provide an understanding of the combustion characteristics of aviation fuel-hydrogen blends in internal combustion engines at elevated pressures and temperatures to achieve zero emissions in aviation.