Flowfield measurements in an unstable ramjet burner

This paper describes the flowfield in the flame region of an unstable laboratory ramjet burner. The steady and unsteady components of the velocity field are obtained using a conditional sampling laser-Doppler velocimetry technique. The vorticity field is also derived from the measured velocity field. It is shown that combustion instability in the ramjet burner is accompanied by unsteady vortex shedding at the flame holding region. The vortex shedding occurs at the frequency of instability, and it periodically distorts the flame front causing a cyclic variation of the flame area.