Combustion Science and Technology, Vol.177, No.5-6, 1023-1047, 2005
Methane-air Markstein numbers from measurements of thermoacoustic instability
Markstein numbers characterizing the influence of stretch on the speed of thin laminar flames are determined computationally for lean and rich methane-air mixtures using results from a recent experimental study of thermoacoustic instability in a Taylor-Couette burner. A model describing the response of a thin laminar flame to acoustic flow-field excitation, which is found to exhibit dependence of thermoacoustic-instability characteristics on Markstein number, is used to determine Markstein numbers from measurements of the critical acoustic-velocity amplitudes associated with the onset of the secondary thermoacoustic instability. The model accounts for the Saffman-Taylor influence of viscosity on thermoacoustic instability for adiabatic flame propagation between closely separated walls.