A Comparative Investigation of Tip-Loss and Compressibility Correlations for Blade Element Momentum Theory Propeller Performance Analysis

This paper presents an in-house BEMT solver implementing state-of-the-art literature models of tip-loss and compressibility to evaluate the accuracy and effectiveness of different combinations in both low-speed and high-speed operating regimes. The BEMT code is integrated with six tip-loss and two compressibility models and used to predict the performance of the two-bladed, three-bladed, and four-bladed versions of the Clark-Y 5868-9 low-speed NACA propeller and the eight-bladed NASA SR-2 high-speed rotor. Two pitch angle distributions, respectively of 25◦ and 35◦ at 75% of blade radius, are considered for Clark-Y 5868-9 NACA propellers analysis. Additionally, the NASA SR-2 rotor performance is evaluated in both the incompressible and compressible regimes, corresponding to Mach 0.2 and Mach 0.8 cruise speed, respectively. The aerodynamic characteristics of the airfoil sections are determined from XFOIL and validated against the available experimental data. The thrust coefficient, power coefficient, and net efficiency curves are computed for a wide range of advance ratios. The results provided by the different correlation combinations are compared with the reference lifting-line solver XROTOR and the available experimental data. The outcome is critically discussed to provide general guidelines on code customization to optimally reproduce higher-fidelity data via BEMT modeling, depending on the operating conditions.