Laser Induced Ignition and Plasma Spectroscopy (LI2PS) Applied to a Non-premixed Hydrogen-air Combustor
Résumé
Laser induced ignition has a potential for several applications such as upper-stage rocket engine ignition device because of its possible high reliability. The laser induced ignition itself has several strong points such as accurate time and impinged energy evaluation capability. The present combined Laser Induced Ignition and Plasma Spectroscopy (LI2PS) have additional potential of measurement to the above-mentioned laser induced ignition in terms of exact local composition of the mixture at the ignition point and for the ignition time. Because the classical power meter classification is not suitable for the present gaseous composite measurement methodology, a novel calibration scheme is proposed for gaseous analysis. We tested non-reactive (helium) case and reactive and ignition (hydrogen) case with a small hydrogen-air burner which is a single injector model of the scaled hypersonic engine under development. At first, the overall capabilities of the gaseous composite measurement are demonstrated with helium as the simulated fuel composite. It is shown that the calibration requires only on the dependencies such as of nitrogen excitation and nitrogen-hydrogen ratio without power meter requirements. Then to illustrate the use of such single shot approach to the combined ignition and plasma spectroscopy case, this methodology is applied to a non-premixed hydrogen-air burner. In this case, the calibration is based on hydrogen excitation and hydrogen-oxygen and hydrogen-nitrogen ratio. Results showed that the local gaseous measurements well correspond to the success/failure criteria, which can not be clearly seen in the past measurement of global fuel equivalence ratio. This result shows that the presently introduced LI2PS would become an important tool when dealing with partially premixed or diffusion flame ignition.