Abstract: To enhance the gas-liquid mixing efficiency, foam expansion ratio, and drainage time in compressed air foam fire suppression systems while ensuring effective firefighting performance, a dual-blade double-helix gas-liquid mixer with internal gas-external liquid configuration was developed. OpenFOAM-based simulations validated that the dual-blade double-helix gas-liquid proportioning mixer with internal gas injection demonstrates superior mixing performance, where optimized internal double-helix geometry significantly improves mixing efficiency. An experimental platform was established to comparatively evaluate three configurations: T-shaped mixer (without turbulence generators), conventional SK static mixer, and the proposed dual-blade double-helix mixer. Tested parameters including foam expansion ratio, drainage time, and pressure loss demonstrated the proposed mixer's superior performance. High-flow-rate experiments confirmed the mixer's scalability and adaptability, making it suitable for various large-scale compressed air foam fire suppression systems.

Key words: compressed air foam system, gas-liquid mixer, mixing efficiency, foam expansion ratio, drainage time