Numerical investigation of the aerodynamic interaction between a tiltrotor and a tandem rotor during shipboard operations

Abstract Complex rotorcraft-to-rotorcraft interference problems occur during shipboard operations, and have a negative impact on safety. A vortex-based approach is used here to investigate the flow field and unsteady airloads of a tiltrotor affected by the wake of an upwind tandem rotor. In this work, the blade aerodynamics is modelled using a panel method, and the unsteady behaviour of rotor wakes is modelled using a vortex particle method. The effects of the ship and sea-surfaces are accounted for via a viscous boundary model. The method is applied to a 1/48th scaled model of a CH-46 operating on a model-scale Landing Helicopter Assault ship. The predicted vertical velocities at the location of the downstream V-22 are compared with Computational Fluid Dynamics and experiments carried out at NASA Ames Research Center. The results show that the predicted vertical velocities compare reasonably well with experiments and Computational Fluid Dynamics. A V-22 tilt-rotor placed in the wake of the CH-46 is also simulated, and rolling moments of the V-22 are calculated to show the effect of the upstream CH-46 wake.

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