Numerical analysis of the impact of charge size on the combustion mechanism and radiation-enhanced effect in Mg/PTFE/Viton pyrolants

Magnesium/polytetrafluoroethylene/Viton (MTV) pyrolants are a typical type of infrared radiation agent capable of emitting intense infrared radiation during combustion. This study systematically investigated the influence of MTV charge size on combustion characteristics and infrared radiation properties through a combination of numerical simulation and experimental methods. Experimental results demonstrated that increasing the charge size significantly enhances the radiation intensity across the near (1–3 µm), mid (3–5 µm), and far (8–14 µm) infrared wavelength bands. Through data fitting, a quantitative relationship was established showing that both infrared radiation intensity and radiation area increase quadratically with charge size expansion. This finding provides a theoretical foundation for the engineering design and practical application of infrared radiation agents. Additionally, based on the energy dissipation concept (EDC model) and the Realizable k-ε turbulence model, numerical simulations were conducted on the combustion processes of five different MTV charge sizes (Ø18 mm, Ø30 mm, Ø42 mm, Ø78 mm, Ø118 mm). The results indicated that larger charge sizes prolong the presence of anaerobic zone products, broaden the thermal radiation range, increase the reaction heat release, and enhance convective heat transfer, thereby accelerating flame propagation. This study presents, for the first time, a quantitative analysis of the relationship between infrared radiation characteristics and charge size in such agents, and confirms that the infrared radiation capability of MTV is significantly enhanced through the synergistic effects of multiple microscopic mechanisms.