A Numerical Study on the Impact of Dynamic Distortions in Total Inlet Pressure on the Stability and Performance of an Aero-Engine's Axial Fan

In preliminary jet engine design, uniform inlet conditions are typically assumed for the compression section, although real-world engines operate under non-uniform inflows that significantly affect the compressor and overall engine performance. For aerodynamic engineers, minimizing performance degradation under such variations is critical. Previous numerical investigations have modeled inlet distortions as temporally invariant. This study presents the first assessment of fan performance under dynamic total pressure distortion. The results enable detailed characterization of unsteady distortion effects and their implications for compressor design. A stability analysis based on the rotational stall mechanism quantifies compressor response under clean and distorted inflow scenarios. The propagation speed of stall cells decreases from 37% of rotor speed in clean conditions to 35% under dynamic distortion. Stall cells increase from 1.82 to 2.01 while their size expands across the entire rotor passage. Overall, dynamic total pressure distortion compromises fan stability by amplifying the severity and onset of rotational stall.