Large Eddy Simulation of Flow around a Propeller of a Multirotor Unmanned Aerial Vehicle

Abstract

Large eddy simulation (LES) is conducted to study the flow characteristics around a propeller of a multirotor unmanned aerial vehicle (UAV). The propeller consists of two blades, and the geometry of blades varies along the spanwise (radial) direction. A global dynamic subgrid-scale model (Park et al. 2006

Lee et al. 2010) is used for the subgrid-scale stress tensor. An immersed boundary method is imposed to satisfy the no-slip condition on the propeller surface in a non-inertial reference frame (Kim and Choi 2006). The Reynolds number based on the tip velocity and the chord length at the 75% span is 73,000. The lift and torque coefficients from the present numerical simulation are in good agreements with those from experiments. The flow is attached on the surface of the propeller up to 60% span, and tip vortices are generated near the tip of the propeller during the rotation. To predict the performance of the propeller, the sectional lift and drag coefficients are obtained along the spanwise direction and compared with models derived by using the classical thin airfoil theory and actuator momentum theory, showing good agreements.