Liquid sheet breakup and atomization of marine gas oil in a pressure-swirl atomizer: Experiments and viscosity-dependent prediction models

This study experimentally investigated the atomization characteristics of Marine Gas Oil (MGO) using a pressure-swirl atomizer. Spray behaviors were comparatively evaluated using three working fluids -water, Jet A-1, and MGO- to examine the influence of liquid properties on atomization characteristics. The spray structures were visualized using the shadowgraphy technique, and droplet size were measured using a Phase Doppler Particle Analyzer (PDPA). The acquired images were analyzed through image processing to quantitatively evaluate the liquid sheet breakup length, wave amplitude displacement, and maximum wavelength. The experimental results showed that MGO, which has the highest viscosity among the tested fluids, produced the smallest air-core area and exhibited distinct liquid sheet breakup characteristics compared with the low-viscosity fluids, water and Jet A-1. The liquid sheet breakup length was longest for MGO, whereas it was shortest for Jet A-1. In contrast, the wave amplitude displacement on the liquid sheet surface increased with increasing injection pressure and decreasing viscosity and surface tension. The amplitude ratio of the waves formed on the liquid sheet ranged from 1.18 to 3.80. A comparison between the theoretical maximum wavelength ( λ _max,theory ) proposed in previous studies and the experimentally measured wavelength ( λ _max,mea ) showed similar trends for water and Jet A-1, whereas λ _max , _theory underestimated the wavelength for MGO. As a result, the initial droplet diameter calculated based on λ _max,theory exhibited an opposite trend compared with the droplet size measured by PDPA. Based on the experimental findings, new correlations for predicting the liquid sheet breakup length and mean droplet size were proposed.