Scattering Characteristics of Fire Smoke and Dust Aerosol in Aircraft Cargo Compartment

Photoelectric smoke detectors, commonly used in aircraft cargo compartments, have high false alarm rates, which may result in huge economic losses and threaten flight safety. Dust aerosols are conventionally considered the main reason for this. Distinguishing dust aerosols from fire smoke by considering the difference between their scattering characteristics using a relatively simple combination of optical elements is crucial for reducing the false alarm rate. According to the relevant provisions for fire smoke and dust specified in the aerospace standard (AS 8036A) of the Society of Automotive Engineers (SAE) and considering the common cargo types, we studied the scattering characteristics of three types of aerosols, including six non-flaming fire smokes, four flaming fire smokes, and two dust aerosols, through numerical calculation and experimental methods. The results showed that these aerosols have different light scattering characteristics for forward and backward scattering due to particle size, morphology, etc. Considering these differences, we distinguished fire smoke from dust aerosols and reduced the false alarm rate in photoelectric smoke detectors in aircraft cargo compartments using an optimised optical structure design with dual wavelengths of 405 and 850 nm and dual scattering angles of 45° and 135°.