Study on infrared properties of low altitude multi-nozzle engine exhaust plume

Infrared properties of multi-nozzle rocket exhaust plume at low altitude were investigated. The heat flux method was adopted to solve the radiative heat transfer for exhaust plume. The 2~5 μm microwave infrared properties of a four nozzles engine exhaust plume including spectral radiances, inband radiances and infrared images were simulated at different altitudes, and compared with the infrared properties of the rocket with single nozzle. The influences of nozzle spacing, detect angle and flight altitude to plume infrared signatures were analyzed. The results show that the spectral radiative selectivity of multi-nozzle exhaust plume is similar to the single nozzle plume, while there is not linear relationship between the two peak values. For low altitude four nozzle engine plume, the infrared properties are enhanced when the nozzle spacing increases, and the radiation intensities increase when the flight height increases.