QUANTITATIVE RAMAN IMAGING INVESTIGATIONS OF MIXING PHENOMENA IN HIGH-PRESSURE CRYOGENIC JETS

A two-dimensional Raman technique was used to investigate mixing pheno mena of cryogenic jets under both supercritical and transcritical cond itions. The aim of this study was to enlarge the experimental data bas is for modeling purposes and to provide quantitative information to he lp to improve the design of injectors for high-pressure rocket engine combustion chambers. Cryogenic nitrogen, which served as substitute fo r Liquid O-2, was injected into N-2 at room temperature at pressures u p to 6.0 MPa. The liquid N-2 jet could be atomized by a coaxial H-2 fl ow. Raman scattering was generated with a XeF excimer laser. The resul ting signal images were discriminated against background by spectral f iltering and preferential detection of light with a polarization corre sponding to the polarization of the laser, thus making use of the cons erved polarization of the Raman-scattered light. The Raman images were converted into density distributions of N-2 and H-2, respectively, as well as into temperature distributions for a variety of experimental conditions. (C) 1998 Optical Society of America.