Fluid Dynamics of a Confined Zero-Net-Mass-Flux Jet with Application to Assisted Dry Powder Inhalation

Zero-net-mass-flux jet (ZNMFJ), has emerged as a promising actuator in fluid dynamics due to its ability to generate a jet without requiring additional mass injection 1. This study explores the application of ZNMFJ to enhance dry powder inhaler (DPI) technology, particularly for patients with respiratory impairments. Conventional DPIs are highly dependent on strong inhalation by the patient, limiting their effectiveness for vulnerable populations such as infants, the elderly, and individuals with chronic asthma. In addition, a significant fraction of drug particles often deposit in the mouth and throat regions rather than reaching the lungs. To address these challenges, this study has investigated a novel ZNMFJ-assisted DPI device (Figure 1) by integrating the zero-net-mass-flux jet into the DPI mouthpiece, consisting of a circular tube with either radial or tangential inflows close to the exit of ZNMF jet. The ZNMFJ actuator provides additional axial momentum to the mouthpiece exiting airflow, aiming to improve drug particle entrainment and targeted lung delivery. Particle image velocimetry (PIV) was employed to measure the 2-component - 2-dimensional (2C-2D) instantaneous velocity field to characterise the unsteady jet induced by the ZNMF jet at the exit of the circular tube mouthpiece. These results offer insights into how the ZNMF jet can be harnessed to manipulate airflow and particle dynamics in a medical device. This work sets the foundation for developing one of the first non-passive DPI systems with enhanced therapeutic efficiency.