1D interferometric Rayleigh scattering velocimetry and thermometry using VIPA

Abstract

The work introduces a VIPA-based interferometric Rayleigh scattering instrument for tracer-free, simultaneous temperature and velocity measurements along a 1D volume. A virtually imaged phased array (VIPA) replaces the Fabry-Perot etalon conventionally used in interferometric Rayleigh scattering, allowing the extension of the technique from 0D (point or multi-point) to 1D. The Rayleigh-Brillouin spectrum is a function of pressure and temperature and can be used for temperature diagnostics in isobaric flows. A reference leg based on a Fabry-Perot (FP) etalon provides real-time monitoring of the laser wavelength drift during the experiment. The accuracy and precision of the measurements are estimated from measurements in laminar flows, and the technique is then demonstrated in a heated turbulent jet of air.