A correlation of aviation fuel temperature effect on mean drop size in pressure swirl spray

The effect of fuel temperature on the spray characteristics of Jet A-1 aviation fuel at various injection pressures discharged from a pressure swirl atomizer was investigated. A two-dimensional phase Doppler anemometry system was used to measure droplet size, and a laser sheet imaging system was employed to take high-quality spray images. The properties of Jet A-1 aviation fuel, especially the viscosity, showed a large variation according to the fuel temperature. Optical measurement results revealed that the atomization characteristics vary significantly depending on the fuel temperature, particularly in the low-temperature region. Spray structure at higher temperatures exhibited a more developed pattern with a wider angle and standard transition from a bulk liquid into ligaments and droplets when the viscous effect was not high enough to disrupt the atomization process. The spray angle dramatically decreased with decreasing fuel temperature and with increasing viscosity and decreasing the injection pressure. The spray structure was unstable and did not develop at low temperature and low pressure. The currently available correlations to predict the Sauter mean diameter of pressure swirl nozzles were deficient in providing good agreement with the experimental data when the fuel temperature was altered. The viscosity in these models was then written as a second-order polynomial, and good agreement with the experimental data was achieved.