Experiment on the influence of flow number of the pilot-stage centrifugal atomizer on ignition performance of internally staged combustor

Ground ignition and high-altitude ignition are important performance indexes of a combustor. In this study, an internally-staged combustor and five pilot-stage centrifugal atomizers with engineering scale were developed. Flow characteristics of these atomizers were studied under the atomizer pressure drop of 0.3 MPa-3.50 MPa, and the flow number of atomizers was obtained. Under the combustor relative air pressure drop of 1.5%-5.5%, the ignition performance of the internally-staged combustor was studied at normal inlet temperature with both normal and negative inlet pressures. In the ignition experiment, only the pilot-stage atomizer worked in the fuel system. The results indicated that, at normal inlet temperature and normal inlet pressure, the lean ignition fuel/ air ratio kept increasing as the combustor relative air pressure drop increased from 1.5% to 5.5%. With the same relative air pressure drop, the ignition envelope could be widened by reducing the pilot-stage flow number. On the other hand, under normal inlet temperature and negative inlet pressure, only the pilot-stage flow numbers of 5.0 and 7.3 at the relative air pressure drop of 1.5% showed successful ignition, while ignition was not successful in other conditions or with other pilot-stage flow numbers. Based on the Lefebvre ignition model, an empirical correlation with prediction errors less than 5% was proposed for lean ignition fuel/air ratio of various pilot-stage flow numbers in the internally-staged combustor at normal inlet temperature and normal inlet pressure.

Automated summary

Ground ignition and high-altitude ignition are important performance indexes of a combustor. In this study, an internally-staged combustor and five pilot-stage centrifugal atomizers with engineering scale were developed, and their flow characteristics and ignition performance were studied. The results showed that the combustor relative air pressure drop and pilot-stage flow number had an impact on the ignition performance.