Low-temperature fuel spray characteristics of a rotary atomizer in aviation gas turbine combustors

Under low-temperature conditions, such as high-altitude re-ignition, the atomization performance of gas turbine fuel nozzles varies with the physical properties of the fuel. However, for rotary atomizers, the atomization characteristics of low-temperature fuels remain insufficiently understood. Therefore, this study investigated the low-temperature fuel spray characteristics of a rotary atomizer. The rotary atomizer was operated at rotational speeds of 2000 − 10,000 rpm and supplied with Jet A-1 at temperatures between +20 °C and − 10 °C. The fuel distribution inside and outside the nozzle was investigated as a function of fuel temperature using high-speed imaging. The fuel discharge flow rate from individual nozzle orifices was measured using a fuel collection device, and the droplet size distribution was measured using optical diagnostic equipment. At room temperature, the supplied fuel formed a wavy liquid film on the cavity wall due to gravity, resulting in a maximum discharge flow rate deviation exceeding 60% and noticeable variations in spray shape depending on the orifice position. As the fuel temperature decreased, the discharge flow rate deviation and spray shape non-uniformity were reduced due to increased fuel viscosity, while the mean droplet size increased. The spray modes at the orifice exit were classified based on the liquid Weber number and Ekman number, and semi-empirical correlations were proposed to predict the spray droplet size.