The Validation of a Parametric Leading Edge Model for Probabilistic CFD Analyses of Post-Service Compressor Airfoils

Abstract The impact of geometric variation of compressor airfoils due to manufacturing scatter and operational effects on the aerodynamic performance is a well-addressed topic in the research field of turbomachinery. Thereby, the airfoils’ leading edge (LE) shapes are highly relevant to their aerodynamic behavior, potentially causing increased losses and separation. In previous probabilistic computational fluid dynamics (CFD) analyses, the LEs were usually modeled as semi-circles or semi-ellipses, whereas their noticeable deviation from these simplified shapes is given comparatively little attention. The study at hand aims to fill this gap by introducing a parametric model for the quantification and parametric recreation of the variability of high pressure compressor (HPC) LE shapes. A set of digitized mid stage HPC rotor blades originating from several jet engines with differing fields of operation are used for the demonstration of the introduced approach. The individual LE 2D-contours are extracted on multiple sections over the blade’s height and compared to a symmetric reference shape. This yields characteristic difference curves enabling the detailed quantification of the variability with a minimum amount of parameters. The derived parametric model allows the statistical reproduction of the measured variability, which is geometrically and aerodynamically validated in the following. The approach’s capabilities in regard to probabilistic CFD analyses are demonstrated by conducting and evaluating two- and three-dimensional flow simulations. Furthermore, the observed geometric variability is linked to the rotor row’s aerodynamic behavior highlighting its importance for the performance variance of HPC rotors.