Abstract: Existing high-expansion foam fire extinguishing technology still faces several challenges and its effectiveness needs improvement. To address this, this paper proposes a large-aperture air-water swirling jet high-expansion retardant foam fire extinguishing technology that requires no on-site power supply. Its working principle is analyzed, and experiments were conducted on foam extinguishing agent component optimization, internal parameter optimization of the air-water jet foam generator, retardant concentration optimization, and comparative tests of liquid fire extinguishing using different air-driven foam generators. The results indicate that the foam extinguishing performance is influenced by the composition ratio of the foam agent, the type of foam generator, the structural parameters of the air-water jet foam generator, and the concentration of the retardant. Optimal foaming performance was achieved with a mass ratio of 5:3 of Sodium Dodecyl Sulfate (SDS) to Sodium Secondary Alkyl Sulfonate (SAS) and a mass concentration of 1.5 g/L for Coconut Monoethanol Amide (CMEA). For the air-water jet foam generator, the optimal foaming performance occurred at a compressed air flow rate of 18 m³/h, a nozzle aperture of 10 mm, using the No. 2 jet tube, a throat-to-nozzle distance of 250 mm, and a foam mesh size of 12 mesh. The optimal fire extinguishing performance was obtained at a retardant mass concentration of 8 g/L. Comparative tests demonstrated that the large-aperture air-water swirling jet foam generator outperformed both the small-aperture air-water jet foam generator and the compressed air foam generator in all foaming and fire extinguishing performance indicators, achieving superior fire suppression effectiveness.

Key words: air-water swirl jet, compressed air high-expansion foam, large aperture, retardation, liquid fire extinguishing characteristics