Acoustic parametric instability, its suppression and a beating instability in a mesoscale combustion tube

The present work reports thermo-acoustic instability in a mesoscale tube of diameter 8 mm (> quenching diameter) and length 702 mm. Mixtures with Lewis number, Le~ 0.8 (rich C2H4/O2/CO2), 1.05 (lean C2H4/O2/CO2) 1.34 C2H4/O2/N2) are used. Several new flame responses observed. For lower burning velocity mixtures, extinction is observed due to heat loss when primary transforms secondary for all Le mixtures. However, parametric cellular structures which characteristic only 0.8. It proposed based on calculations experiments that will be two times larger than the wavelength instability. If doesn't allow formation structure whirling counter-rotating flames instead structures. Suppression acoustic higher mixtures Le>1 its mechanism discussed. range SL, beating CO2 diluted Le>1, where pressure oscillation motion show oscillations frequency around 15 Hz. This believed caused by non-linear interaction pulsating front combined radiative convective loss. Due dilution, losses could play significant role inducing