The Air and Droplet Dynamics of a Soft Mist Inhaler

This presentation investigates the coupled air and droplet dynamics of a soft mist inhaler using 2C–2D PIV for airflow measurements and hybrid PIV/PTV for droplet tracking. The study characterises the inhaler mouthpiece flow under different airflow pressure drops, water injection pressures, measurement planes, and homogeniser-flow conditions. The results show that the airflow centreline velocity decays downstream and becomes nearly invariant after approximately 2D, reaching about 30–50% of the near-nozzle velocity. Homogeniser flow suppresses near-nozzle recirculation and reduces axial variation in the far-field airflow profiles. Droplet velocities closely follow the airflow field, indicating strong aerodynamic coupling, while the water-jet direction is sensitive to co-flow asymmetry and its speed is largely independent of injection pressure over the tested range.