Effect of discrete spectral resolution on calculation of the infrared characteristics of engine plume

Finite volume method(FVM) model and its solution procedure were established.And corresponding FORTRANprogram was developed to simulate the plume infrared characteristics,in2～5 μm,of a standard example engine that flies in atmosphere.This study focuses on the effect of the discrete spectral resolution in FVMon the infrared calculation precision.The result shows that the source directional spectral radiative intensity becomes,after absorption along a 0.88 km horizontal sea level path,gradually independent of the discrete wavelength when the discrete spectral resolution increases.When the number of discrete equal intervals of the infrared wavelength of 2～5 μm in FVMis more than150,the infrared spectral radiative intensity emitted from the plume is independent of the discrete spectral resolution.