Fragmentation dynamics of single agglomerate-to-wall impaction

Area of Science:

• Particle science and engineering
• Fluid dynamics
• Pharmaceutical engineering

Background:

• Understanding particle-agglomerate behavior is crucial for dry powder inhaler (DPI) performance.
• Agglomerate de-agglomeration during impaction influences drug aerosolization and delivery.
• Existing models require detailed experimental validation for accurate predictions.

Purpose of the Study:

• To quantitatively characterize the de-agglomeration of single agglomerates upon wall impact.
• To investigate the influence of particle size and air velocity on fragment characteristics.
• To provide data for validating computational models of de-agglomeration in DPIs.

Main Methods:

• High-resolution shadowgraph imaging of single agglomerate-wall impacts.
• Controlled experiments varying constituent particle size (3-7 μm) and air velocity.
• Advanced image processing to analyze fragment size, velocity, area, and aspect ratio.

Main Results:

• De-agglomeration fragment populations exhibit a bimodal distribution of area and aspect ratio.
• Increasing air velocity disrupts this bimodal dispersion.
• Bimodality diminishes over time after impact.

Conclusions:

• The study provides a quantitative platform for de-agglomeration behavior analysis.
• Observed fragment dispersion patterns are sensitive to air velocity and time.
• Findings support the development and validation of computational fluid dynamics (CFD) models for DPIs.