The influence of nozzle deflection on fluid dynamic and infrared characteristics of a two-dimensional convergent–divergent vectoring exhaust system

Abstract

Superior maneuverability and good infrared stealthy properties are two key points of the future aircraft. A two-dimensional convergent–divergent (2D-CD) vectoring exhaust system can improve the maneuverability of aircrafts and has been widely applied to the latest generation aircrafts. Understanding fluid dynamic and infrared radiation characteristics of the 2D-CD vectoring exhaust systems under different conditions of the nozzle deflection is very crucial, which can provide significant information for the suppression of the infrared radiation property of the 2D-CD vectoring exhaust system. In this paper, by means of computational fluid dynamics, the fluid dynamic and infrared radiation characteristics of the 2D-CD vectoring exhaust system are studied at subsonic cruise status with nozzle deflection angles from 0 to 20°, and the results are compared with those of the baseline axisymmetric exhaust system. The results indicate that the fluid dynamic performance of a properly designed 2D-CD vectoring exhaust system is equivalent to the fluid dynamic performance of the baseline axisymmetric exhaust system. When the nozzle deflection angle is less than 5°, the mass flow and thrust force of the 2D-CD vectoring exhaust system are almost unchanged, and with the increase of the nozzle deflection angles, the mass flow and thrust force decrease rapidly. The thrust force deflection angles lag behind the nozzle deflection angles all the time, and as the nozzle deflection angle increases, the difference between them decreases. The direction of the maximum infrared radiation of the 2D-CD vectoring exhaust system deflects with the deflection of the nozzle, and the mean integrated infrared radiation intensity of the exhaust system decreases with the increase of nozzle deflection angles.