Numerical study on infrared characteristics of aero-engine exhaust plume considering TRI effects

This study developed the ESTRI numerical simulation software for infrared characteristics of hydrocarbon-fueled exhaust systems by integrating Embedded Large Eddy Simulation (ELES) and the Atmospheric Transmissivity Weighted Multi-Species Wide-Band (ATWMSWB) k-distribution gas radiation model. The reliability of the ELES and ATWMSWB models was verified by comparing with measurement data of flow field parameter distributions for both subsonic and supersonic nozzle exhaust plumes, as well as Line-By-Line (LBL) calculation results for transient flow field remote sensing infrared imaging. The computational accuracy of the ESTRI software for the time-averaged infrared signals of turbulent gas jets was further validated by comparing numerical results with measured integral radiation intensity data from a small aero-engine exhaust system plume. Based on this, a numerical study was conducted to investigate the impact of three often-neglected factors in exhaust system infrared characteristic calculations-Turbulence-Radiation Interaction (TRI), humidity of engine ingestion ambient air, and real-gas effects-on the infrared signals in the 3.7–4.8 μm wavelength band. The results show that TRI significantly influences the infrared characteristics of gas jets, with its effect slightly increasing with detection distance increase. The water vapor ingested from ambient air by the engine has little impact on the near-field infrared signals of the exhaust plume but can account for up to one-third of its far-field infrared signals. Real-gas effects also have a noticeable influence on the infrared signature of gas jets.