Numerical Study of Fuel Spiking Induced Surge in a Small-scale Aircraft Engine

Flow instabilities, such as surge and stall, in fans and compressors seriously threaten the performance and structural integrity of aero engines. Accurate prediction of flow behaviours related to these aerodynamic instability phenomena has long been focused on. In this paper, a full-engine model for a small-scale turbofan engine is established based on the threedimensional Unsteady Reynolds-Averaged Navier-Stokes (URANS) governing equation. Based on the model, the unsteady simulation is conducted for the fuel spiking process to force the small-scale turbofan engine into surge. The simulation successfully captured the flow instability behaviours in the engine, and a detailed analysis of the main aerodynamic parameters of engine sections, axial force, and power balance of the engine within one surge cycle is conducted. In this case, the compressor enters deep surge, and the fan enters mild surge. Moreover, the fan rotor blades suffer the most severe axial force among all the blade rows. According to the unsteady flow behaviours, the compressor rotor blades at the trailing edge suffer the most serious damage caused by the reversed flow shock wave.