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

In order to solve the difficulty of the existing compressed air foam system with low FER and difficult in having both the FER and range. A new type of foam generator for CAFS was designed, an air-liquid coaxial foam generator, which produces foam with high FER (the ratio of the foam volume to the volume of the foam solution) and large output momentum. In this paper, experiments on the foam production performance of a gas-liquid coaxial jet foam generator were carried out with different parameters, such as liquid flow rate, gas flow rate, and foam output end diameter. The variation of FER, foam half-life, range, foam volume, and compressed air utilization rate with the experimental parameters were analyzed. The results show that the foaming performance of the foam generator tends to rise in the range of 8-12.4 m/h at a fixed gas flow rate, the FER and foam half-life are negatively related to it, and the foaming performance tends to decrease in the range of 12.4-18 m/h. The best foaming performance was achieved when the liquid volume of the foam generator was 12.4 m/h. For the liquid volume value in different intervals, the foaming performance varies with the air supply volume. When the liquid volume is higher than 12.4 m/h, increasing the air supply volume is beneficial to improve the foaming performance, and when the liquid volume is lower than 12.4 m/h, increasing the air volume does not improve the foaming performance. The effect of the diameter of the foaming chamber on the foaming performance is not monotonic, and an optimum value exists. Compared with similar devices, the gas-liquid coaxial jet foam generator has strong advantages in FER and range and has better application prospects for fire control in restricted spaces.