Diagnosis of High Speed Flows using Filtered Rayleigh Scattering

This paper presents results from measurements performed in a sonic underexpanded jet using filtered Rayleigh scattering (FRS), and the results demonstrate that this technique is capable of obtaining quantitative measurements of density and its spatial distribution. The underexpanded jet is surrounded by a low speed jet in a co-flow arrangement thus minimizing the presence of dust in the entrained flow. A molecular iodine filter is used to reject unwanted background scattering and thus enhance the flow features, and further, is also used to modify the frequency spectrum of the light scattered from the flow field molecules. Schemes to calculate densities with and without the presence of the filter are presented and are used to obtain time averaged density.

Diagnosis of High Speed Flows using Filtered Rayleigh Scattering Conference Paper