Study on Gas-Liquid Coaxial Jet Foam Generator and Its Foaming Characteristics

Area of Science:

• Fire Safety Engineering
• Fluid Dynamics
• Materials Science

Background:

• Existing compressed air foam systems (CAFS) face challenges with low foam expansion ratio (FER) and limited range.
• Improving both FER and operational range is crucial for effective fire suppression.

Purpose of the Study:

• To design and evaluate a novel air-liquid coaxial foam generator for CAFS.
• To address the limitations of existing systems by enhancing foam expansion ratio (FER) and output momentum.
• To investigate the impact of various operational parameters on foam generation performance.

Main Methods:

• Experimental analysis of a gas-liquid coaxial jet foam generator.
• Systematic variation of parameters including liquid flow rate, gas flow rate, and foam output end diameter.
• Evaluation of key performance metrics: FER, foam half-life, range, foam volume, and compressed air utilization rate.

Main Results:

• Optimal foaming performance achieved at a liquid flow rate of 12.4 m³/h.
• Foaming performance initially rises and then declines with increasing liquid flow rate (8-18 m³/h) at a fixed gas flow rate.
• Increasing air supply volume enhances performance when liquid volume exceeds 12.4 m³/h; it does not improve performance below this threshold.
• Foaming chamber diameter shows a non-monotonic relationship with performance, indicating an optimal value exists.

Conclusions:

• The gas-liquid coaxial jet foam generator demonstrates superior FER and range compared to similar devices.
• This novel generator offers significant advantages for fire control applications, particularly in confined spaces.
• The findings provide valuable insights for optimizing CAFS technology for enhanced fire suppression capabilities.