LASER-INDUCED SPARK FLAMEHOLDING IN SUPERCRITICAL, SUBSONIC FLOW

Laser-induced spark flameholding was demonstrated, and the effect of n ow and optical parameters on the flameholding distance was investigate d, A pulsed Nd:YAG laser was used to induce electrical breakdown in a now and ignite a methane/air gas mixture, The laser energy, pulse freq uency, and methane concentration were varied, and the flameholding dis tance as a function of these parameters was determined, Results were t hen compared to calculated values, For a flow speed of approximately 1 10 cm/s and a laser repetition rate of 15-20 Hz, the flameholding dist ance, defined as the downstream distance from the spark to the positio n where continuous combustion is achieved, was found to be on the orde r of a few centimeters, Experimental results were extrapolated to dete rmine the pulse frequencies required for flameholding at hypersonic fl ow speeds, The potential application of solid-state, continuous-wave l asers to spark flameholding is also considered.