Analysis of Aerodynamic Trim and Rotor/Propeller/Wing Interference Characteristics for High-Speed Composite Helicopter in Hover

The special configuration of rotor, fixed wing and thrust propellers is employed in the X3 high-speed composite helicopter to achieve Vertical Take-off and Landing (VTOL) and high-speed cruise capability. In hover state, the wing is in the downwash flow of the rotor, resulting in negative wing lift and increased rotor thrust. At the same time, the propellers on both sides of the wing produce opposite thrust to balance the rotor torque, which also affects the aerodynamic performance of the wing. To investigate the aerodynamic interference of rotor/propeller/wing, firstly, the quasi-steady flow models with medium precision were used to evaluate the isolated rotor and propeller performance quickly. Then the fast algorithm for aerodynamic trim of composite helicopters was applied with the collective pitches of rotor, left and right propellers determined. Finally, the unsteady flow models with high precision were used to predict the components performance under flow interference around the whole helicopter flow field. To validate the simulation model, Robin helicopter are used as a benchmark for rotor/fuselage interference. The front and rear fuselage surface pressure predicted by the calculation agree well with the experimental data. Based on verification, the combination of wing, propeller and rotor as well as the whole helicopter flow field simulations show that rotor/wing flow interaction is the most significant in hover. There are 10% thrust increase for the rotor and 1100N negative lift for the wing.