pisarapaksuus

Pisarapaksuus, meaning “droplet thickness” in Finnish, refers to the characteristic size of liquid droplets produced in sprays, atomization, and aerosols. In practice it is synonymous with the droplet size distribution and is usually described by mean diameters and measures of dispersion. Pisarapaksuus affects evaporation rate, deposition, and optical properties in coatings, agricultural spraying, and inhalation therapies.

Measurement and metrics: Droplet size is typically characterized by volume-based diameters (Dv), number-based diameters (Dn), the Sauter mean diameter D[3,2], and median diameters (Dv0.5, Dn0.5). Methods include laser diffraction, phase Doppler interferometry, dynamic light scattering, and high-speed imaging. Each technique has strengths and limitations for polydisperse sprays, and the choice of method often depends on the size range and the liquid’s optical properties.

Influencing factors: Fluid properties such as viscosity, surface tension, and density affect droplet formation. Device design and operating parameters, including nozzle type, atomization pressure, and flow rate, play major roles, as do environmental conditions like temperature and humidity. Application-specific requirements determine the target size range: finer droplets can improve coverage and evaporation, while larger droplets may enhance deposition and reduce drift.

Implications and control: Achieving the desired pisarapaksuus involves formulation changes and process adjustments, such as modifying nozzle geometry, fluid composition, and operating settings. A clear understanding of the droplet size distribution is essential for predicting spray behavior, ensuring quality control, and optimizing performance in practical applications.