粗糙元/振动对低 Re 数压气机叶栅边界层转捩影响的高精度数值研究

This study employs a spectral element-based direct numerical simulation (DNS) solver to investigate the boundary layer transition of low-Reynolds-number compressor cascades subjected to surface roughness elements and blade vibration. The roughness elements or rough surfaces are represented using an embedded boundary method, while the vibration-induced body force is introduced via a moving coordinate system. We examine the transitional boundary layer flow over a flat plate with favorable–adverse pressure gradients and localized three-dimensional roughness, as well as over the suction surface of a cascade blade featuring a random cylindrical roughness array and its coupling with blade-normal vibration. The effects of different effective slopes, skewness, and streamwise locations of the roughness on the near-wall drag characteristics and downstream transitional flow features are quantified, and the transition mechanisms on the suction surface of compressor cascade blades are elucidated. The results show that, roughness elements trigger distinct transition mechanisms on the suction surface of the blade, depending on whether they are located in the favorable or adverse pressure gradient region. Under the coupling of vibration, the boundary layer becomes thinner, the high-loss region is reduced, and in the outer region of the turbulent wedge, the wall-normal vortex tilting term in the vorticity equation plays a dominant role in the generation of streamwise vortices.