Simulation study on fire extinguishing system of ultra-fine powder extinguishing agent in helicopter engine compartment

Abstract

The design of the engine compartment fire extinguishing system determines the release, flow and dispersion characteristics of the ultra-fine powder extinguishing agent (UPEA), which affects its effectiveness. The simulation of the UPEA fire extinguishing system in the engine compartment of a helicopter model was carried out, and the results of the study showed that, the maximum mass flow of UPEA particles at the nozzle of the fire extinguishing system pipe was 5.2 kg/s, and the injection time was 0.31s. At the same inlet air temperature in the engine compartment, the smaller the inlet air flow, the longer the engine compartment UPEA concentration maintenance time. At the same inlet flow, the higher the inlet air temperature, the shorter the duration of UPEA concentration in the engine compartment. The duration of the lowest extinguishing agent concentration was 0.70s at an inlet air temperature of 121°C and an inlet air flow of 0.423kg/s. Under different inlet air flow and temperature conditions, the UPEA concentration at all 12 monitor points in the engine compartment was maintained for more than 0.5s, meeting the design requirements. The research results have guiding significance for fire extinguishing system design of certain helicopters.