Experimental and numerical analysis of multicopter rotor aerodynamics

Unmanned Aircraft Systems (UAS) are state of the art in aerospace industry and are involved in many operations. While initially developed for military purposes, nowadays com- mercial applications with small scale UAS, such as multicopters, are quite common. Accurate engineering tools are required to asses the performance of these vehicles and optimize power consumption. Thrust and power curves of rotors used by small scale UAS are essential to design efficient vehicles. The lack of experimental data as well as accurate prediction models to evaluate rotor coefficients over the UAS flight envelope are two major limitations in UAS science. In addition, Reynolds numbers based on the chord for small scale rotors at normal rotation rates are usually smaller than 100, 000 resulting in degraded performance. In the following paper, experimental data on small scale multicopter propulsion systems are presented and combined with a Computational Fluid Dynamics (CFD) model to describe the aerodynamics of these vehicles in low Reynolds conditions. The commercial CFD software STAR-CCM+ will be used to perform CFD simulations which will include both a dynamic grid with a time accurate analysis and a static grid steady state approach solving Navier-Stokes equations in an adequate reference frame. Numerical simulation results for a conventional UAS propeller are corroborated by the experimental data and suggest the proposed approach is able to properly describe thrust and torque coefficients within the Reynolds numbers range characterizing the UAS flight envelope