Numerical Analyses of Surge Process in a Small-Scale Turbojet Engine by Three-Dimensional Full-Engine Simulation

Surge is a typical aerodynamic instability phenomenon in the compressors of aeroengines. The surge can lead to severe performance degradation and even structural damage to the engine and the air vehicle, making it a longstanding critical concern in the industry. Analyzing and understanding the surge process contributes to enhancing the aerodynamic stability of designed compressors. Previous research in this field often focuses solely on the compressor itself while neglecting the mutual interaction between the compressor and other components in the entire engine system. This study investigates the compressor surge process within an integrated engine environment using a full-engine three-dimensional Unsteady Reynolds-averaged Navier–Stokes (URANS) simulation method for the entire engine system, validated through variable geometry turbine experiments on a small turbojet engine. The result demonstrates that the integrated three-dimensional simulation approach can capture the primary flow characteristics of the compression system during surge within an integrated engine environment. Under the influence of the variable geometry turbine, the studied small turbojet engine enters a state of mild surge. This paper also investigates the changes in aerodynamic forces during surge and reveals the two-regime surge phenomenon that exists during the engine surge.