Abstract
Experiments about change of pipe length, diameter, and combustion quantity under stoichiometric condition were conducted to clarify what kind of influence abrupt pipe expansion has on combustion oscillation in the tubular flame burner. The sound pressure was measured at the tube exit by a microphone. It is found from the experimental results that installation of pipe expansion restrain heat release oscillation including the fundamental frequency of about 400 Hz and enlarge range of stable combustion. But when pipe length is longer than a certain value, combustion oscillation is always generated regardless of combustion quantity and pipe diameter. This is why mutual sound pressure level was amplified by axial mode of columnar resonance wave and heat release oscillation.
