Exploring the Role of Physical and Chemical Properties on the Ignition and Flame Stability of Liquid Fuels with a Spray Burner and Fuel Ignition Tester (FIT)

摘要

Liquid fuels have different physical and chemical properties which can affect the atomization, evaporation and mixing processes inside heat engines, including turbine and reciprocating internal combustion engines. In this work, the relationship between the fuel's properties and its ignition/flame stability is investigated. A spray burner was designed and manufactured to simulate the mixing dynamics experienced in a turbine engine combustor capable of delivering high fuel and air co-flow rates. The flame behavior and stability have been studied by measuring the flame liftoff heights and blowout limits for different single component fuels at different fuel and air flow conditions. In addition, a Fuel Ignition Tester (FIT) was used to investigate the impact of volatility and local enrichment on ignition delay. Results indicate a strong influence of fuel volatility and atomization on the flame stability. The less volatile/heavier fuels have higher liftoff heights, while the fuels with smaller droplet sizes and higher volatility blowout easier than less volatile fuels and those which atomize into larger droplets. In the FIT, it was noticed that the local equivalence ratio defined by the fuels volatility has more effect on the ignition delay than the global air fuel ratio. As a result, n-dodecane ignites faster than n-heptane, despite the having a lower measured global equivalence ratio.