ANALYSIS OF AERODYNAMIC INTERFERENCE CHARACTERISTICS AND AEROACOUSTICS 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. The wing is in the rotor downwash, resulting in negative wing lift and increased rotor thrust. The propellers on both sides of the wing produce opposite thrust to balance the counter torque of the rotor, and the thrust magnitude is related to the hovering attitude. At the same time, the rotor/propeller/fuselage aerodynamic interference constitutes the unique aerodynamic noise characteristics of the helicopter. To investigate the aerodynamic interference of rotor/propeller/wing and space noise distribution, 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 control parameters and attitude parameters determined. After that, the unsteady flow models with high precision were used to predict the components performance under flow interference around the whole helicopter flow field. Finally, based on the FW-H equation of permeable surface and IDDES model, the whole helicopter noise was predicted in hover. To validate the simulation model, Robin helicopter was used as a benchmark for rotor/fuselage interference. The UH-1H rotor was used to verify noise performance in hover condition, and the SR-2 propeller was used to verify discrete noise characteristics. The calculated results were agreed well with the experimental data.