Large eddy simulation of flow past a multirotor propeller in forward flight condition

We investigate flow characteristics of an isolated multirotor UAV propeller under various advance ratios using large eddy simulation. An immersed boundary method in a non-inertial frame of reference with a dynamic global subgrid-scale model is used for the simulations. The flow field and aerodynamic coefficients from the present simulations are in good agreements with those from experiments. The simulation clearly shows the interaction of trailing vortex sheets with hub and tip vortices, which results in complicated non-axisymmetric vortical structures. With increasing advance ratio, blade sectional analysis reveals complete loss of lifting capability near the hub region in the retreating side. Large variation of the effective angle of attack during the blade rotation produces large oscillatory longitudinal moment which may be detrimental to vehicle stability. The detailed effect of advance ratio on the flow structure will be discussed at the presentation.