Study on the correlation of the altitude ignition parameter and lightoff air fuel ratio for jet engine combustors

摘要

The ignition performance of a jet engine is affected by the configuration of the combustor; pressure, temperature and velocity of air at the combustor inlet; fuel type, temperature, injected fuel flow distribution and droplet size; and by the ignition energy and air-fuel ratio. Lefebvre theoretically obtained a parameter that has quantitative relationship with the factors for combustor inlet pressure, temperature and velocity of air, ignition energy, and pressure loss. Although the parameter is very simple, easily applicable, and useful in designing a combustor or determining the effect of combustion conditions on the ignition performance, sufficient data are not yet available. Here three full scale combustors are used to perform ignition tests by extensively varying combustor inlet pressure (P{sub}3), temperature (T{sub}3) and velocity (V{sub}(ref)) as in an actual high altitude operation. The ignition parameter "I=P{sub}3{sup}0.5T{sub}3{sup}1.5/V{sub}(ref)" that is corrected in Lefebvre's theory revealed the good correlations with the light-off air-fuel ratio to express the lean ignition limits.