CONDITIONS FOR THE EXCITATION OF A LAMINAR KINETIC SINGING FLAME

Experimental studies have been conducted of the concentration regimes of excitation and silence of acoustic instability of a laminar kinetic singing flame with changes in composition, flow rate, and initial tem perature of a propane-air mixture. Measurements of the distribution in tensity of the varying component of the emission of the CH radical at a wavelength of 4315 Angstrom and of the phase difference between osci llations of pressure and of heat-release rate along the flame height h ave shown that the major portion of varying heat release for sustainin g and amplifying pressure oscillations, in accordance with the Rayleig h criterion, occurs as a result of periodic changes in the surface are a near the tip of the flame cone. A relation has been, established bet ween the change in the phase shift and the appearance of concentration al and temperature regions of excitation and silence of acoustic oscil lations.