Numerical study on the influence of turbine swirl on exhaust system

Abstract

This article employed numerical methods to investigate the aerodynamic, thermal, and infrared characteristics of last-stage turbine swirl on a two-dimensional convergent divergent (2D-CD) exhaust system with an afterburner under varying bypass ratios. The research results indicate that the swirl diminishes the thrust coefficient and flow coefficient of the 2D-CD exhaust system with an afterburner. At a bypass ratio of 0.2, the thrust coefficient and flow coefficient decrease by 0.65% and 1.07%, respectively. When the bypass ratio is relatively small, the swirl flow leads to a decrease in the temperature of the afterburner heat shield. Conversely, when the bypass ratio is relatively large, the opposite occurs. The maximum temperature of the heat shield increases by up to 7.2% (bypass ratio = 0.35), while the average temperature decreases by up to 7.1% (bypass ratio = 0.2). The swirl causes an increase in the temperature of the divergent section heat shield, with the most significant deterioration observed at a bypass ratio of 0.25, resulting in a maximum temperature increase in 12.2%. Swirling flow shortens the length of the jet flow, and as the bypass ratio reduces, this attenuation effect becomes more pronounced. When the bypass ratio is 0.2, the length of the core area decreases by 40.3%, and the infrared intensity of the narrow-side jet flow decreases by 12.5%. Overall, on the XOY detection plane, the maximum decrease in infrared intensity is 11.5%, and the maximum increase is 11.7%. On the XOZ detection plane, the maximum decrease in infrared intensity is 15.9%, and the maximum increase is 5.7%.