Experimental investigation on combustion instability of liquid oxygen and methane flame

Experimental results of a test campaign on the interaction of a cryogenic LOX/CH4 spray flame with an acoustic excitation are given. Liquid oxygen and gaseous methane are injected with a shear coaxial injector. The flame was visualized by detecting the OH emission with a frame rate up to 27 kHz. Simultaneously shadowgraph images were also recorded to visualize the flow field. The flame behavior under different chamber pressure and different mixture ratio is compared. A pressure modulator device was used to excite acoustic pressure oscillations in the combustion chamber. The first transversal and the first longitudinal combustion instability could be excited during hot fire tests. Two strong low frequency instabilities were found under high frequency external disturbance. A lifted flame has been observed under the experimental conditions and the characteristic of the lift-off distance is discussed.