Direct Numerical Simulations and Boundary Layer Analysis in Compressor Blade Channel at Various Reynolds Numbers

Abstract The current study investigated the boundary layer (BL) characteristics in the V103 compressor blade channel under a series of Reynolds number (Re) conditions (Re = 1.367 × 105, Re = 1.506 × 105, and Re = 1.645 × 105) using direct numerical simulation (DNS). Detailed analyses were conducted on the BL, including the separation bubble, transitions, and reattachments on both the pressure and suction surfaces. The analyses suggest that Re has a very limited impact on the size of the laminar separation bubble (LSB) on the pressure surface. However, the LSB on the suction surface significantly shrinks with increasing Re. Moreover, the BL thickness identification method based on Bernoulli's principle was applied to complex internal flows for the first time, and achieved an accurate determination of BL integral quantities. The transition locations, which were estimated using the BL shape factor, shifted upstream with the increase in Re on both pressure and suction surfaces, causing the earlier reattachment points. The study also investigated velocity profiles in the turbulent region of the BLs and successfully extended the inner-layer law from the traditional flat plate to the current curved surfaces, demonstrating the validity and accuracy of the inner-layer law's formulations in describing the turbulent boundary layer (TBL) velocity profile. These findings provide both numerical and physical insights into the complex-geometry BLs in the compressor blade channel at low-to-medium Re, offering strong potential for optimizing blade design.