Simultaneous measurements of refractive index, surface tension, and evaporation rate of Jet A fuel.

ABSTRACT

Simultaneous measurements of refractive index, surface tension, and evaporation rate in pendant droplets have been conducted in water, ethanol, n-heptane, diesel, and Jet A fuel in a temperature range of 20°C-50°C at atmospheric pressure. The dispersion of the refractive indices has been determined by means of rainbow refractometry. The surface tensions have been measured based on the pendant droplet shape analysis. The Young-Laplace equation and the numerical model have been applied to precisely obtain surface tension from the balance between the droplet distortion of gravity and restoring the force of surface tension. The evaporation of the fuels has also been studied with pure droplets of a few millimeters in diameter in a temperature-controlled environment. The shadowgraph technique has been performed for the precise measurement of the droplet size change with a long-working-distance objective (10× magnification). The evaporation rate has been determined by the temporal rate of droplet diameter change extracted from the subsequent images. The experimental data in this work is compared with the previous work to validate the accuracy and estimate uncertainty. Furthermore, the simultaneous multi-property measurement of Jet A fuel (POSF 4658) has been conducted. These properties of the aviation fuel can be used in computation and modeling to further improve the knowledge of jet injection (atomization and evaporation) and practical combustion processes.