Low Reynolds Number Effects in Compressor Blade Design

Abstract

The trend for the engine design goes to smaller core engines to increase the bypass ratio and reduce the weight. With the decrease of core engine size, also the Reynolds Number decrease locally. This leads the focus within the design process of the axial compressor on the accuracy of the numerical models which are used for the simulation. Therefore, an experimental and numerical study was carried out to evaluate the state-of-the art design process for axial compressor bladings concerning the low Reynolds number effects within the flow. As study approach a linear cascade was used. Whereby the experiments were performed at the Transonic Cascade Wind Tunnel TGK of the DLR in Cologne and for the numerical simulations DLR in-house flow solver TRACE was conducted. The investigation was carried out at an inlet Mach number of 0.60 and a Reynolds number of 0.15 x 106. The comparison shows a significant discrepancy which is based on the current weakness of the turbulence and transition modeling at a RANS simulation regarding the viscosity effects at lower Reynolds numbers. Additional simulations were performed at a higher Reynolds number of 0.9 x 106 to substantiate this interpretation. Here, a good agreement with the equivalent measurement results at this Reynolds number is shown.