Numerical study on exhaust flow field characteristics of irregular stern engine in high-altitude chamber

The irregular stern structure is often used in the exhaust nozzle of high-bypass turbofan engines, but there is limited research on the exhaust flow field characteristics of this structure in high-altitude simulation tests. This research investigates the influence of such configurations by comparing Mach number distributions, vortex structures, and thrust performance, while also varying the secondary flow mass rate in the test chamber to assess its influence on the internal flow field. The results demonstrate that non-axisymmetric stern structures induce a kinetic energy deficit in the primary flow, generating extensive separated vortices around the stern that reduce the core Mach number and incur thrust losses within 0.5%. Conversely, increased secondary flow mass rate suppresses primary flow recirculation and enhances thermal regulation capability within the chamber.