Developement of Gas-Phase Mixing Measurements in Turbulent Spray Flows Using Filtered Rayleigh Scattering

摘要

In this paper we will describe recent advances made in our laboratory towards the development, validation, and application of a filtered Rayleigh Scattering technique for measurements of gas-phase concentration fields in the presence of liquid-phase droplets. Preliminary studies of the maximum level of droplet scattering attenuation attainable utilizing an injection-seeded, Q-Switched Nd:YAG laser in conjunction with a molecular iodine filter will be presented. These results demonstrate the correlation of the spectral purity of the laser with the effectiveness of the molecular filter in suppressing particle (Mie) scattering. Improvements in spectral purity and the maximum Mie scattering rejection as a result of implementing an external etalon into the optical path of the laser output will be demonstrated. Initial validation studies of the FRS technique also are presented in which gas-phase information is extracted from a droplet-laden turbulent jet. Comparisons of suppression capabilities with and without the external etalon are presented, allowing for an assessment gains offered in implementing the etalon. Finally, we present initial results from an evaporating spray jet of acetone into air.