计及叶片前缘周向不均匀源项的弯掠叶片流动机理

Bowed and swept blades have been widely used in the transonic fan/compressor of aircraft engines to harmonize the conflicts between high loading, high through-flow, high efficiency, and acceptable stall/surge margin. However, these blades can also induce stress, vibration, and stability problems. Therefore, to better apply the advantages of bowed and swept blades to fans/compressors and reduce the complexity of their spatial structure, we need a deeper mechanistic understanding of bowed and swept aerodynamics. In this paper, the circumferential averaging method is used to derive a quantitatively describable circumferential fluctuation source term, which reveals that the circumferential fluctuation induces a re-equilibrium of the fan/compressor inlet flow field different from that of a straight blade and which in turn affects the design incidence angle of each base element of the bowed and swept blade and produces changes in the flow field and performance characteristics of the fan/compressor. This mechanism of the curved (bowed and swept) blade is verified by numerical simulation and Stereoscopic Particle Image Velocimetry(SPIV) experiments. The results show that the circumferential fluctuation source term in the curved blade can break the radial equilibrium of the original inlet field, leading to the radial migration of the inlet field, generating the spanwise differences of the key parameters of the inlet field, changing the spanwise distribution of the incidence angle, and thus affecting the overall flow field performance. Meanwhile, an analytical model and a machine learning model are constructed for the circumferential fluctuation source terms affecting the inlet flow field to release the traditional assumption of a uniform flow field of inlet air, to facilitate the aerodynamic design and analysis of the 3D bowed and swept blade.