航空模型燃料与氢气掺混微尺度燃烧数值模拟

The combustion of a Jet A-1 surrogate (69% C₁₀H₂₂， 11% C₉H₁₈ and 20% C₉H₁₂) and hydrogen in pure oxygen was simulated in a two-dimensional three-step back stage micro-scale combustor. The effects of hydrogen mixing ratio and inlet gas flow rate on the combustion characteristics in the combustor were analyzed. The results showed that all the flames can be stabilized before the first stage of the micro burner (3 mm away from the micro burner inlet). With the increase of hydrogen mixing ratio，the flame position gradually moved towards the micro burner inlet，the flame length was shortened，and the high-temperature area inside the micro burner reduced，the maximum temperature decreased，the upstream combustion intensity was higher but the downstream combustion intensity was lower，the mass fractions of CO and CH₄ decreased，the fuel cracking occurred closer to the micro burner inlet and the mass fractions of the cracking products decreased. With the increase of inlet gas flow rate， the high temperature zone of combustion reaction expanded，the flame center position and flame front moved and stretched towards the micro burner outlet，the influence of hydrogen mixing ratio on the wall temperature decreased， the OH mass fraction along the micro burner centerline increased， the CO₂ mass fraction decreased，the CH₄ mass fraction increased，and the cracking reactions occurred closer to the micro burner outlet and the mass fractions of the products increased. These results indicated that at low inlet gas flow rate，mixing a small amount of hydrogen can obtain high wall temperature and high energy. Low inlet gas flow rate may affect the chemical reaction in the combustion zone and reduce the amount of OH generated upstream. The increase of hydrogen mixing ratio and the decrease of flow rate can cause more obvious fluctuation of CO mass fraction. The hydrogen mixing ratio was 25% when the CO₂ mass fraction reached the highest amount. At high hydrogen mixing ratio and low inlet gas flow rate， acetylene was mostly generated by direct cracking of the fuel，and only a small amount was generated by secondary cracking of propylene.