In confined environments such as aircraft, an increase in mass impacts the overall system's performance, thus requiring sophisticated management. To verify whether the performance characteristics of fire extinguishing systems used in aircraft are satisfied, in this study was built a 1:1 scale test model. We examined the influence of the initial charge state and nozzles. Further, it measured the pressure inside the pipelines and vessels where multiple nozzles are installed to identify the flow and diffusivity characteristics of HFC-125 inside the pipelines and vessels. At a charging ratio of 54%, the initial pressure drop was smaller, and the lowest pressure before the bubble release point appeared 0.26 s later than when the charging ratio was 76%. The average pressure of each nozzle was 275.8 kPa higher under a charging ratio of 54% than 76% and increased further when the average concentration change was 54%, indicating that diffusivity increased. Although improvements occurred according to the charging ratio, the improvements according to the HFC-125 charging mass were more significant.
Keywords: Aircraft fire extinguish system; Charging ratio; Diffusivity; HFC-125; Pressure recovery.
© 2023 The Authors.