A Study of Combustion in Simple Combustion Chamber

抄録

This paper deals with the low frequency type of oscillations in a simple combustion chamber where the fuel used is propane. The phenomenon was found to be closely connected with the progressive flame necking from the results of flame photographs by a high speed camera and the frequencies of oscillations were able to be caloulated as a Helmholtz resonator. From both results mentioned above and measurements of pressure drop along the combustion chamber, it was found that the oscillations were caused by the negative gradient of the characteristic curve which represents the relation between the pressure drop and the secondary air velocity in the vicinity of the flame necking. Some theoretical analyses were made and a differential equation of Van der Pol type was obtained. The analytical values of the frequencies well agreed with the experimental results and an example of oscillation patterns on phase-plane was in good agreement with that of oscillograms.