Abstract: Foam rheological properties are important for engineering design and hydraulic calculation of foam fire extinguishing system. The dynamic viscosity and shear stress of compressed air foam under different working conditions were measured by a rotary rheometer, and the rheological properties and rheological model of a new type of high stability compressed air foam are analyzed. The results show that the rheological constitutive equation of the new high stability compressed air foam based on polysaccharide polymer conforms to the Herschel-Bulkley model within 5 minutes and belongs to the yield pseudo-plastic fluid, and the foam dynamic viscosity decreases with the increase of shear rate. The shear stress and dynamic viscosity of the new high stability compressed air foam gradually increase with the increase of polysaccharide polymer premix mixing ratio, gas-liquid ratio and foaming time. The rheological properties of the compressed air foam decreases with the increase of polysaccharide polymer premix mixing ratio. When the mixing ratio of polysaccharide polymer premix is increased from 37.5% to 50.0%, the shear stress is almost unchanged. The rheological properties of the high stability compressed air foam decreases gradually with the increase of gas-liquid ratio and foaming time.

Key words: fire extinguishing agent; compressed air foam; high stability; rheological properties; gas-liquid ratio; mixing ratio