Aerodynamic Performance and Flow Interaction of the Intermeshing Rotors in Hover

Aiming at the complex aerodynamic interference problem of intermeshing rotors, a numerical simulation method was established suitable for aerodynamic analysis of the intermeshing rotors. The method solved the three-dimensional unsteady Reynolds Average Navier-Stokes(RANS) equations to simulate the flow field, and used the moving embedded grids to simulate the rotor motion. The hovering experiment results of coaxial rotors verified the accuracy of the method. The method was used to simulate the flow field of intermeshing rotors in different states, and calculate the thrust coefficient and hover efficiency. The results were compared with those of single rotors and coaxial rotors. The results show that there are strong vortex-vortex and propeller-vortex interactions in the intermeshing-rotor flow field. The tip vortices of the rotor blades are intersected near 90°/270°. The thrust coefficient and hovering efficiency of the intermeshing rotor increase with the increase of the rotor center spacing, and the change is small with the intersection angle. The hovering efficiency of the intermeshing rotors is 3% to 8% higher than that of single rotors and coaxial rotors at the same collective pitch.