An experimental study on the low-temperature spray characteristics of aviation Jet A-1 fuel with rotational speeds in a slinger-type atomizer

A slinger nozzle is a device that atomizes fuel using centrifugal force generated by rotation of the gas turbine shaft. This nozzle is easy to design and manufacture and has excellent atomization performance at high speed rotation, making it suitable for small gas turbine engines. In this experimental study, the spray characteristics of a slinger nozzle were investigated using a high-speed camera and a 2-dimensional phase Doppler anemometry (PDA) system, and the velocity components and the mean droplet size (SMD) of the spray were obtained at rotational speeds of 5000 to 30,000 rpm. Water and Jet A-1 were used as working fluids, and due to the difference in the physical properties of the fluids, column- and sheet-shaped sprays appeared, respectively. The sheet-shaped spray was found to be favorable for initial droplet generation. Accordingly, Jet A-1 disintegrated and formed initial droplets faster than water at the spray center of Y/d_o = −1 to +1. The droplet sizes of the water and Jet A-1 sprays crossed at a nozzle rotational speed of 17,000 rpm, and thereby, the dominant variables that affect droplet formation, such as viscosity and surface tension, could be identified based on this rotational speed. As the temperature of the Jet A-1 decreased, the sheet-shaped spray changed to ligament-shaped sprays at the nozzle orifice exit, and the droplet size increased due to the increased viscosity, which disturbed the ligament breakup. Finally, mathematical expressions were presented to predict the mean droplet size (SMD) of slinger nozzle sprays based on the previous results and experimental data. These apply to the determination of the ignition condition of the slinger-type gas turbine combustor.