Effects of a dielectric barrier discharge plasma actuator on pressure-nozzle liquid spray characteristics: An experimental study

The application of dielectric barrier discharge plasma actuators (DBD-PAs) to liquid sprays has potential in various applications and industrial processes. Different phenomena may occur when cold plasma interacts with sprays, including changes in spray morphology and variations in droplet size and velocity. The present work experimentally investigates the effect of a DBD-PA discharge in air on a distilled water spray generated by a pressure nozzle. An innovative injection system was designed and built, integrating a commercial injector as the grounded electrode within an annular DBD-PA. An experimental campaign was conducted to analyze changes in spray morphology, droplet size, and velocity distributions. Two different injection pressures were tested, and alternating DBD-PA operation under sinusoidal voltage excitation was explored. Measurements were performed using diffused back-illumination technique (for morphology and droplet sizing) and laser Doppler velocimetry (for mean and unsteady velocities). The DBD-PA applied voltage and the corresponding discharge current were recorded, which allowed the actuator's dissipated power to be assessed through electrical characterization and monitored throughout the experiments. The results show that the DBD-PA effectively modifies the droplet size distribution, with larger droplets concentrating near the interior of the spray. At the same time, velocities at the spray periphery were reduced, indicating a redistribution of momentum within the spray. These observations suggest that the actuator can influence both the morphology and dynamics of the pressure-nozzle spray, potentially enabling improved control over atomization and deposition patterns.