Optical diagnostic of temperature in rocket engines by coherent Raman techniques

This article reviews the study of Raman line shapes of molecular species involved in reactive media, such flames or engines, at high temperature and high pressure. This study is of interest from a fundamental as well as from a practical point of view with regards to the CARS temperature diagnostic of GH2–LOX combustion systems. We will particularly draw attention to recent investigations by means of Stimulated Raman Spectroscopy (SRS) in H2–H2O mixtures at temperature up to 1800 K. Whereas H2–X systems usually exhibit large inhomogeneous effects, due to the speed dependence of the collisional parameters, the absence of such apparent inhomogeneous signatures in the H2–H2O system allowed us to model the broadening coefficients with simple polynomial laws. These laws permit extrapolations with a narrow confidence interval, as required for temperature measurements. The applications of these results to the temperature diagnostic on the small-scale facility MASCOTTE at ONERA will be described. To cite this article: F. Chaussard et al., C. R. Physique 5 (2004).