During the overall process of designing the turbofan engine

the model for predicting the signature of infrared radiation was established.With the method for calculating the fluid dynamics

the influence of the total temperature and total pressure at the inlet of convergent exhaust system of turbofan engine on the temperature distribution at plume centerline was estimated; the overall process of designing the turbofan engine was required and the approximate formula for calculating the temperature distribution at plume centerline was achieved. The result shows that the dimensionless distance corresponding to the dimensionless temperature at plume centerline is proportional to the total pressure of the inner duct

the bypass duct and total temperature of the bypass duct at the inlet of convergent exhaust system of turbofan engine

but inversely proportional to the total temperature of the inner duct.Therefore

it can be concluded that the summed-up experience formula of temperature distribution at the plume centerline of turbofan engine agrees well with the numerical results.