Thermally Induced Acoustic Oscillations in a Pipe : 3rd Report : oscillations induced by a premixed flame in a pipe

Abstract

Acoustic oscillations induced by a premixed flame in a pipe have been studied analytically and experimentally in comparison with the gauze tones which have been reported in the previous papers. The flame-induced oscillations may most possibly be generated when the dimensionless current velocity in the pipe is around unity as in the case of the gauze tones. The ratio of the reaction rate to the frequency is another important parameter indicating the possibility of oscillation growth by the flame, and when the ratio is small the oscillation cannot grow. The relation between the upper frequency limit of the oscillations generated and the current velocity in the pipe has been examined experimentally, and it agrees well with the analytical result. The calculated amount of energy supply can be supposed to coincide with the measured energy dissipation considering the inaccuracy of the experiment and the assumptions used in the analysis.