Characterization of a Low-Pressure Spray Atomizer via Tomo-PIV and High-Speed Imaging

Conventional atomizer designs often rely on high pressure drops or complex internal geometries to generate fine sprays. This study introduces a novel atomizer that produces a pulsating spray with minimal energy input and a simple design. The pulsation arises as the liquid level in a pressurized reservoir falls below an internal suction tube, allowing air to intermittently enter the flow and entrain small slugs of liquid. This creates an alternating sequence of air–water–air slugs, which break up rapidly upon ejection from the nozzle. The result is a naturally pulsating spray, similar to air-blast atomization, but achieved through a single-orifice device with no moving parts. To quantify the pulsation behavior, we establish a relationship between pressure drop and slug formation frequency by measuring the volume and timing of the entrained slugs. High-speed imaging and Tomo-Particle Image Velocimetry (PIV) are used to characterize droplet size, breakup length, velocity, and spatial distribution. The results demonstrate efficient atomization at low pressure, suggesting that this design could be valuable in applications where energy efficiency and simplicity are critical.