Numerical evaluation of the static performance of a small propeller comparing traditional and transitional turbulence models

Abstract

Propeller design and performance influence the operational efficiency of drones, and with the increasing use of small UAVs, accurately determining the performance of small propellers becomes crucial. CFD is considered a highly accurate method, and turbulence models are essential for CFD simulations, especially when dealing with low Reynolds number flows, such as those in small propellers, since transitional laminar-turbulent flows are difficult to predict. The objective of this work is to investigate the use of transition-sensitive models to identify the conditions under which their use is truly necessary, as they are computationally intensive. A 3D-printed propeller, designed from the SDA 1075 airfoil, was tested under static flow conditions on a test bench, with thrust and torque measurements. Fully turbulent models were used in the simulation, and the results were compared with measurements between 2,000 and 8,000 rpm. Consistent results were obtained for Reynolds numbers above 60,000. For Reynolds numbers below 60,000, the results were not very accurate. Therefore, transition-sensitive models capable of capturing laminar separation were used, and consistent results were obtained for Reynolds numbers below 60,000. This was demonstrated by the propeller's aerodynamic coefficients and the images of laminar separation bubbles captured by the simulation.