Predicting Lean Blowout Limit of Combustors Based on Semi-Empirical Correlation and Simulation

Abstract

A method named characteristic curve of flame volume is achieved for lean blowout predictions on the basis of the improved Lefebvre’s model and simulated reacting flows. Three main issues are presented: 1) Based on the results from combustion visualization experiments, Lefebvre’s model is improved regarding its universality for combustor configurations. The flame volume near lean blowout obtained from simulated reacting flow is introduced into the model. 2) Characteristic curve of flame volume is a functional curve of flame volume and fuel/air ratio in a certain combustor and is presented as an “” pattern, with ranging from stable operation to nearly engine-off conditions. The region where the fuel/air ratio ranges from 3 to 10 in characteristic curve of flame volume is the unstable combustion region, and nearly all of the lean blowout points fall in this region. 3) According to the relationship between characteristic curve of flame volume expressed as and the improved Lefebvre’s model expressed as , a method named characteristic curve of flame volume is proposed for lean blowout predictions. By the comparison with experimental data on 26 combustors, the lean blowout fuel/air ratios obtained by the characteristic curve of flame volume method fit well with that obtained by experiments, having maximum and average errors of and between predictions and measurements.