ЛІЧИЛЬНО-ІМПУЛЬСНИЙ МЕТОД ДОСЛІДЖЕННЯ ДИСПЕРСНОЇ СТРУКТУРИ КРАПЕЛЬНИХ ПОТОКІВ, СФОРМОВАНИХ ВІДЦЕНТРОВИМИ ФОРСУНКАМИ

Droplet size distribution governs heat and mass transfer intensity, interfacial area, and the performance of spray-type contact equipment. In dense sprays, optical diagnostics may be difficult, and contact-based techniques remain relevant. Purpose. To develop a methodology for applying an electrical pulse-counting method to determine local and overall characteristics of droplet flows generated by pressure-swirl atomizers. Method. The method records electrical pulses produced when a droplet of conductive liquid bridges two electrodes with variable tip spacing. The pulse-rate dependence on electrode spacing was described by a first-kind Volterra integral equation and reduced to an Abel-type equation. The experimental response was approximated by a one-parameter exponential function. Its parameter was used to determine the volume-based droplet size distribution, modal, median, and 95th-percentile diameters, specific interfacial area, and local volumetric liquid flux. Local distributions were combined into an overall spray distribution by weighting them with liquid flux over the spray cross-section. Results. A one-parameter representation of the droplet size distribution was obtained. Atomizers with one tangential inlet produced a non-uniform circumferential spray, whereas atomizers with two or more inlets generated an almost axisymmetric distribution. At the same pressure drop, the latter produced a 40–50 % greater specific droplet surface area. A dimensionless correlation relating the modal droplet diameter to liquid-film thickness and Reynolds number was obtained. Scientific novelty. A procedure was proposed for converting local measurements of droplet size distribution and liquid flux into a flux-weighted distribution representative of the spray cross-section. Practical importance. The methodology can be used to characterize droplet flows, compare atomizer designs, and select operating and geometric parameters for spray-type heat- and mass-transfer equipment.