ROBUST NONLINEAR FINITE-STATE INFLOW MODEL FOR LIFTING ROTOR COUPLED WITH BLADE FLAPPING

Real-time inflow model for lifting rotor is required for pilot-in-the-loop simulation and flight control design. The recent developed blended inflow model have advanced the state-of-the-art with closed-form solution for all three components of the flow everywhere in the field, including below the plane of the rotor disk both in-wake and out-of-wake. The nonlinearity will be introduced in such blended model to make it more flexible not only for helicopter in cruise condition, but also for helicopter in low speed flight or hover. The dynamic loading for such inflow model will be computed in real-time based on blade element theory. Then the flap motions of blades of lifting rotor will be coupled, and the induced velocity will be solved numerically in the time domain through the simpletic scheme. A Harrington rotor will be studied as an example. The induced velocity in the time domain for such a rotor will be calculated with a specific flight controls.