Non-invasive, spatially averaged temperature measurements of falling acetone droplets in nitrogen atmosphere at elevated pressures and temperatures

Abstract

Mean temperatures of acetone, millimeter-sized, freely falling droplets in a nitrogen atmosphere are studied at two different locations downstream a capillary-type injector. Injection and ambient temperatures have been varied independently between 433 and 513K and pressures from 2 to 6MPa. The ratio of simultaneously measured laser-induced phosphorescence (LIP) and fluorescence (LIF) is shown to be a suitable approach for measuring temperatures in the given conditions. Cumulated uncertainties (2σ) of mean droplet temperatures of ±3K are estimated. The temperatures measured in this study are partly compared to results of previous investigations where droplet temperatures have been estimated by an extrapolation of temperature mixture fraction data in the gas phase obtained from spontaneous Raman scattering. Overall a reasonable agreement has been observed which indicates the applicability of the previous approach for estimations based on the adiabatic mixing assumption and the extrapolation of the Raman-measured data.