Numerical Simulation and Aerodynamic Investigation of the Intermeshing Rotor in Hover

Abstract

Abstract Compared with single rotor helicopter, aerodynamic theoretical model for intermeshing rotor is immature. Aerodynamic modeling for intermeshing rotor is much more complex because of the strong and unsteady interference resulting from two closely rotating blades. Moving Overset Grid technical has been used for the aerodynamic investigation of intermeshing rotor in hovering state. SST k - ω turbulence model was used for the solving of unsteady RANS equations. The simulated result matches well with the experimental data, in which the calculation error for lift coefficient, Ct , is smaller than 4.5%. Firstly, the fluctuation of Ct is periodic with a frequency of 4/rev, which is equal to the total number of blades of the intermeshing rotor. Average aerodynamic loads rise as the increasing of collective angles. Secondly, the maximum induced velocity of the intermeshing rotor is significantly larger than those of the single rotor and the equivalent rotor. Blade-vortex interference and vortex-vortex interference coexist in the flow field of the intermeshing rotor. Finally, three shaft angles, 20°, 24°, 28°, were investigated. Among the calculating cases, the effect of the shaft angles is not monotonous. Maximum hovering efficiency is achieved at θ = 24°.