Experimental investigation of the effect of air/fuel ratio change on JP8 swirl flame characteristics with image processing methods

In this study, the stable combustion ranges and emission values of JP8 fuel, which is used in military aviation, were tested and optimum conditions were determined. The AFR (Air/Fuel Ratio) of the JP8 flame was increased experimentally at constant thermal power in a gas turbine combustion chamber. In the study, AFR were tested as 30/1, 33/1, 36/1, 39/1 and 42/1. A generator with 0.4 swirl number is placed at the burner outlet. Under these conditions, the effect of external acoustic enforcement frequencies on dynamic instabilities at different AFR was investigated. Flame length and thickness data were extracted from the images obtained from the image processing technique. The effect of AFR change on the combustion chamber temperature was examined and pollutant emissions were measured. The results showed that the most stable flame appeared in AFR 33/1 case at 155 and 300 Hz resonance frequencies under acoustic enforcements. Additionally, when the AFR was increased to 42/1, flame instability increased at all frequency values. Moreover, it has been determined that the most optimum mixture in terms of combustion chamber exit temperature and CO emissions is AFR 33/1. There was an increase in NOX emissions by up to 39/1 with the increase in AFR.