Multi-fidelity investigation of low-reynolds number propeller for different design parameters

Abstract

This paper presents a comparative multi-fidelity analysis of a small-scale UAV propeller (2-bladed, 0.3m diameter, NACA 4412 airfoil sections) operating at low Reynolds number. Three aerodynamic solvers, high-fidelity Lattice Boltzmann Method (LBM), mid-fidelity lifting-line free vortex wake (LLFVW) and mid-fidelity vortex lattice method (VLM), are evaluated across a broad range of advance ratios, number of blades, collective pitch settings, and skewed inflow angles. All methods predict consistent trends in thrust and torque as design and operational parameters are varied, with the mid-fidelity models closely replicating trends obtained using the high-fidelity LBM. LLFVW generally overestimates and VLM underestimates the magnitudes of thrust and torque relative to experiments (and LBM), but these biases remain approximately constant over the entire range of each parameter. By leveraging these mid-fidelity tools in place of expensive CFD, computational cost is reduced by over two orders of magnitude, with minimal loss of predictive capability. The results demonstrate that mid-fidelity simulations can reliably capture propeller performance trends at a fraction of the CPU cost, making them attractive for rapid design iterations and surrogate-based optimisation frameworks.