Influence of Liquid Pulsation on the Breakup and Atomization Processes of a Cylindrical Prefilming Nozzle

Abstract Fuel pressure oscillation is common in gas turbine combustors, which is significant to the spray effects of the liquid film. The objective of this experimental study is to figure out the impact mechanism of liquid pressure oscillation on the atomization effects of liquid film, from the aspects of film-waving, break-up, and atomization processes. The frequency range is 0–100 Hz, and the amplitude is 10% and 20% for the inlet liquid pressure. The wave, breakup, and atomization processes of the liquid film are evaluated using a planar laser-induced fluorescence apparatus and a Malvern particle size analyzer. The findings indicate that as the frequency is increased, the breakup performance of the liquid film initially improves, but subsequently declines. Compared with the liquid film without liquid pulsation, an inlet pressure pulsation with a frequency of 40 Hz and an amplitude of 10% can reduce the film thickness, breakup length, and droplet size by 22.6%, 32.9%, and 23.2%, respectively. This is due to the fact that liquid pulsation can increase the film instability, resulting in a thinner film that is more susceptible to breakup, which in turn leads to a reduction in droplet size. However, when the frequency is high, the time interval between cycles decreases, and the liquid wave peak induced by the pulsation cannot be eliminated. Similarly, an increase in amplitude results in a stronger pressure pulsation, which in turn produces a thicker wave peak that is more difficult to break up. This ultimately leads to poor atomization performance. Furthermore, the droplet size exhibits no periodic pulsation, indicating an absence of response to inlet liquid pulsation.