Numerical study on the influence of trailing edge modification on aerodynamic performance and infrared radiation characteristics of turbofan engine exhaust system

To enhance the battlefield survivability of fighter aircraft by reducing the infrared signature of turbofan engine exhaust systems while maintaining aerodynamic performance, this study numerically investigates the variations in aerodynamic characteristics and infrared signatures of axisymmetric and two-dimensional nozzles under different trailing edge modification rates. A self-developed code was employed to solve the variable specific heat Navier-Stokes equations, yielding the thermodynamic state parameters and gas composition distributions within the internal and external flow fields of the nozzles. Subsequently, the radiative transfer equation was solved to obtain the reflected radiation on the inner and outer surfaces of the exhaust system. Based on these results, infrared imaging of the nozzle surface and exhaust plume was generated using a ray tracing algorithm. The results indicate that trailing edge modification has a negligible effect on the nozzle's discharge coefficient, while it reduces the thrust coefficient, with maximum reductions of 3.84% and 4.27% for the axisymmetric and two-dimensional nozzle, respectively. For the axisymmetric nozzle, the infrared radiation intensity in both the forward and rear hemispheres first decreases and then increases with the trailing edge modification rate. At detection angles of 45°, 90°, and 135°, the infrared radiation intensity decreases by 8.30%, 6.21%, and 6.22%, respectively. In contrast, two-dimensional nozzle exhibits a consistent decrease in infrared radiation intensity in both hemispheres with an increasing modification rate, with reductions of 3.43%, 19.11%, and 23.40% at the aforementioned angles.