Modeling droplet size distribution near a nozzle outlet in an icing wind tunnel

The median volume diameter (MVD) and the droplet size distribution (DSD) in an aerosol cloud under icing conditions are investigated. The procedure involves experimental observation of aerosol size distributions in an icing wind tunnel, computing the MVD by applying an empirical formula, and matching a distribution function to experimental data so as to estimate the DSD. Some of the nozzle dynamic parameters (NDPs), i.e., nozzle water and air pressure, are varied throughout the experiments, and droplet diameter is measured near the nozzle outlet. A new empirical formula is proposed that expresses the relationship between the MVD and the NDPs and, compared to previous studies, provides wind tunnel operators with a more convenient technique to estimate the MVD in the operational range of the selected nozzles. Moreover, the least squares fitting technique is used to find the best-fitting distribution function among published empirical relationships intended to model the DSD for nozzle-generated aerosol. The MVD and DSD obtained by this procedure, together with the NDPs and the thermodynamic parameters, may be used to model and control two-phase flows in icing wind tunnels.