Numerical Simulation for The Forward Flight of the Tri-copter Using Virtual Blade Model

Abstract

This paper presents the process of implementing numerical simulation for a tri-copter in forward flight using the open source code OpenFOAM with the library of Virtual Blade Model (VBM). The tri-copter has 0.75-meter radius and 15-Newton weight. Its propulsion system consists of three two-blade propellers typed XOAR PJP-T-L 1245 with12-inch diameter and 4.5-inch pitch. In the first part, the aerodynamic performance of the tri-copter’s frame (not including the propellers) is investigated at the range of angle of attack from -12 degree to 12 degree by simulation in OpenFOAM. Secondly, these force coefficients are exploited in the analytical approach based on the Blade Element Theory (BET) to determine the rotor disk plane angle and the tri-copter’s frame angle for steady, level, forward flight at 15-m/s. Finally, after obtaining the relative angle of -2 degree between the rotor tip-path-plane and the tri-copter’s frame, the simulation for the tri-copter in forward flight including three rotor disks rotating at 4732-RPM will be carried out through the rotorDisksource library of the open source code OpenFOAM. A steady, incompressible solver with k-? SST turbulence model is applied in the simple Foam algorithm. The aerodynamic forces and the dynamic fields surrounding the tri-copter will be discussed in detail, while the effect of tri-copter’s frame on rotor operation will also be considered. Moreover, the results of thrust from each propeller from simulation are compared to that of analytical BET method and that of propeller performance provided by the manufacturer. This comparison proves rational of using virtual disk to replace real propeller in the CFD simulation.