Parametric Modeling of Smoke-Generation Dynamics and Optical Screening Performance of Pyrotechnic Aerosols

The optical masking properties of pyrotechnic obscurant aerosol-generating systems are time-dependent and determined by the interrelationship among aerosol-formation dynamics, radiation attenuation efficiency, spatial distribution, and subsequent dispersion of the aerosol cloud. In this study, we developed a process-parametric approach to compare the smoke formation dynamics and optical masking efficiency of a reference aerosol system and an alternative system, designated Recipe 1. Both systems were evaluated using a common 100 g initial composition mass. Because no independent aerosol-mass-yield measurements were available, this mass was used as the effective aerosol-forming mass in the parametric optical calculations, corresponding to a unit-yield normalization. The adopted extinction coefficients and generation times were treated as representative parametric inputs rather than experimentally measured properties, with optical calculations performed in the visible range of 0.4–0.7 μm. For the reference system, the mass extinction coefficient was assumed to be 4.0 m2·g−1, the initial delay time was 12 s, and the period of intensive aerosol formation was 70 s. For the parametric case designated Recipe 1, these values were set to 5.0 m2·g−1, 7 s, and 45 s, respectively. The calculated integral masking capacity increased from 400 to 500 m2 when the assumed mass extinction coefficient was changed from 4.0 to 5.0 m2·g−1. The optical density in the near-eye region increased from about 8.7 to 10.85. In the case of a larger prescribed-area scenario, the corresponding optical-density values were about 1.93 and 2.41. The calculated critical optical-density criterion Dcr = 1.3 was met in about 22–23 s for the reference system and 12–13 s for the Recipe 1 system. The calibrated model reproduced the prescribed target persistence times of approximately 145 s for Recipe 1 and 160 s for the reference system when the dispersion parameter was calibrated to the midpoint of the corresponding persistence intervals specified in the supporting technical assessment. These results indicate that the combinations of different process parameters determine the maximum optical attenuation level and the duration of the masking effect. Thus, the proposed approach provides a basis for a comparative engineering assessment of aerosol-generating systems. At the same time, the accuracy of the characteristics obtained as a result of the calculation must be verified by time-resolved experimental optical measurements.