关键词: 环境压强, 火源功率, 压缩空气泡沫, 灭火时间, 覆盖范围, 喷射距离, 温度分布

Abstract:

To investigate the fire extinguishing performance of compressed air foam under different ambient pressures and fire source powers, a Computational Fluid Dynamics (CFD)-based numerical simulation was employed. A three-dimensional numerical model was developed and validated, and the foam discharge and combustion processes were analyzed. The extinguishment state was determined based on the CO₂ mass fraction, fuel mass fraction, and reaction rate. Key parameters, including extinguishing time, foam coverage area, discharge distance, and fire temperature distribution, were analyzed, and an empirical correlation for foam extinguishing time applicable to different ambient pressures and fire source powers was established. The results show that within the ambient pressure range of 50-100 kPa, the extinguishing time for two fire source powers (13.85 and 31.84 MW) increase monotonically with increasing ambient pressure. The increase in pressure alters the foam structure and flow characteristics, weakening its spreading and fuel-surface sealing capacity, thereby prolonging the extinguishing process. The foam coverage area remains essentially equal to the oil pool area under all pressure conditions, stabilizing at approximately 10 and 26 m², indicating that ambient pressure has a limited effect on coverage area. The foam discharge distance shows minor variation and remains around 2.7 m, suggesting negligible influence of ambient pressure. After extinguishment, the temperature distribution exhibits spatial non-uniformity: the temperature in regions initially covered by foam decreases rapidly, whereas higher temperatures persist on both sides of the oil pool due to delayed foam coverage, posing a risk of reignition and requiring further cooling.

Key words: ambient pressure, fire source power, compressed air foam, extinguishing time, coverage, spray distance, temperature distribution