ID#: 110
Abstract Title: Propagation of a Flame from the Closed End of a Smooth Horizontal Tube of Variable Length
Session Title: Acoustic Phenomena
Session Date: 7/31/01
Session Start Time: 2:00 PM
Contributing Author: Veyssiere, B.
Organization: Laboratoire de Combustion et de Detonique-CNRS
Country: France
Authors: Steven Kerampran, Daniel Desbordes, Bernard Veyssiere
Short Abstract: Flame propagation has been studied from the closed end to the open end of a tube having a square cross section (40 mm x 40 mm) and a variable length (0.6 m < L < 8.1 m, by steps of 0.5 m). For stoichiometric propane air mixtures, the flame trajectory exhibits an oscillatory behaviour for all tube lengths, while pressure records show oscillations, the frequency of which corresponds to the fundamental mode of vibration of the column of fresh gas contained in the tube. These results corroborates our previous observations made at smaller scale. The major role played by acoustics is displayed and confirmed by experiments performed with mixtures where helium has been substituted to nitrogen. Detailed analysis of the initial stage of flame propagation shows that the flame accelerates as the consequence of the growth of its surface. During this stage, the flame behaves as a piston, thus increasing the pressure and putting in movement the fresh gases in front of it. At a subsequent stage, flame propagation is dominated by the oscillating flow generated during this initial period.