The effect of ozone addition on the combustion characteristics of hydrogen-jet fuel

摘要

Ozone (O- 3 ) addition combustion is a trending technique to enhance the ignition characteristics of hydro-carbon fuel. In this study, the spray ignition characteristics of jet fuel along with hydrogen (H- 2 ) and O (3) seeding were experimentally investigated and numerically simulated with an updated chemical kinetic model. The ignition delay (ID) period of jet propellant 5 (JP-5) with H-2/O-3 addition was measured using a constant volume combustion chamber (CVCC) at 600 K to 818 k, the pressure of 15 bar, equivalence ratio of 0.5. The intake manifold was added with air, H- 2 (10, and 20 volume fraction), and 20 0 0 ppm ozone (O 3 ). In general, pure JP-5 has a shorter ID than those obtained with H (2 )addition. At 600 K, with 10 and 20 H (2) to JP-5, the ID was increased by 18.49, and 35.12 respectively. When O 3 was added, the ID of JP-5 was shortened by 10, while for 10 and 20 H (2) addition, the ID was shortened by 19.25 and 22.5, respectively. An existing jet fuel mechanism was chosen and validated with the previous and the present study experimental ID. The model was in agreement with the practical ID. The H- 2-mechanism rate constants were updated with the recently optimized values available in the literature to reflect the newly obtained experimental data at low temperatures. An existing sub-mechanism of O( 3 )was adopted and combined with the JP-5 model. The updated model was validated with the present study ID data. Good predictions were noticed between the model and JP-5 experimental ID. However, a small devia-tion of 5.01 and 0.71 was found for 10, and 20 H- 2 ID at 600 K. The reaction H (2 )+ OH = H2O + H and HO2 + HO2 = H2O2 + O- 2 were found to be the critical reactions responsible to reduce the systems reactivity and makes the fuels ID to become longer. The O-atom from O 3 was decomposed through the reaction O- 3 + N- 2 = O (2) + O + N (2 ), and O- 3 + O- 2 = O (2) + O + O (2) at an early stage of combustion. Due to H (2 )addition to O 3 and air, the early formation of OH radicals is due to O- 3 + H = O- 3 + OH, which further accelerates the oxidation of the fuel, resulting in a shorter ID. (C) 2022 The Combustion Institute. Published by Elsevier Inc. All rights reserved.