An experimental investigation was made of the behavior
of a small two-dimensional combustion chamber, burning
a uniform mixture of air and fuel vapor under conditions
of high-frequency oscillation or screech. Measurements
were made of the limits of stable screech, the amplitude
and frequency of pressure oscillations over a wide range of
mixture ratio, inlet air temperature, and combustor flow
rate. Spark schlieren photographs and high-speed motion pictures taken of the combustion process showed, in
agreement with other investigations, that the high-frequency
oscillation is accompanied by vortices shed periodically from the flameholder lip with the same frequency as the oscillation. The following mechanism of exciting the oscillations is suggested. A mode of transverse
oscillation is excited as the result of periodic transport
of combustible material, associated with the vortices,
into the hot wake of the flameholder. The vortices, in
turn, are generated at the flameholder lips by the fluctuating transverse velocity. When the ignition time delay lies in the proper range, the phase relationship between oscillations in transverse velocity and combustion intensity is such that the oscillation is amplified
