Simulating inlet total temperature distortion flows in transonic compressor based on time-space collocation method

In the field of aero-engines, the issue of inlet distortion has long been a focus of attention. Due to the significant experimental challenges, research on total temperature distortion is limited. Thanks to advancements in numerical simulation technology, the Unsteady Reynolds-Averaged Navier-Stokes (URANS) method has been employed to study the impact of total temperature distortion on compression systems, but at a high computational cost. This paper utilizes the Time-Space Collocation (TSC) method based on Fourier harmonics, validated with NASA Stage 67, to assess its accuracy and computational efficiency in simulating unsteady flows under total temperature distortion. The TSC method considers the harmonics of conservative variables, transforming unsteady simulations into multiple steady-state simulations, thereby significantly reducing computational cost. Compared to the traditional URANS method, the TSC method considering only inlet distortion harmonics achieves approximately an order of magnitude speedup; when both inlet distortion and rotor-stator interaction harmonics are included, the speedup of the TSC method is halved. At the peak efficiency point, the number of retained harmonics has minimal impact on performance prediction; however, at near stall point, retaining fewer harmonics tends to underestimate the stall mass flow rate and total pressure ratio. The TSC method with different harmonic combinations can reasonably predict the propagation of total temperature distortion and the generation of total pressure distortion. Retaining higher-order harmonics enables more accurate prediction of unstable factors such as flow separation and blockage in blade passages, significantly improving stall margin prediction. For the same inlet total temperature distortion, this compressor is more sensitive at higher rotational speeds, with a greater reduction in stall margin.