A Study On Thermo-Acoustic Instability Of Downward-Propagating Hydrocarbon Flames In A Tube

The combustion response characteristics of downward-propagating hydrocarbon flames were investigated with respect to the mechanism of thermo-acoustic instability in gas turbines and rocket engines. Six different characteristics of combustion response were obtained as a function of laminar burning flame velocity and Lewis number. The acoustic intensity indicated an amplification tendency in high laminar either burning flame velocity or a relatively low Lewis number. In particular, when the laminar burning flame velocity was significantly high, the flame propagation speed increased by the amplified acoustic field. It subsequently caused acoustic and heat losses as well as additional nodes due to the third harmonic at a specific location of the quarter wavelength resonator, resulting in temporary acoustic damping.