Interactional Aerodynamics of the XV-15 Tiltrotor Aircraft during Conversion Maneuvers

Abstract

The high-fidelity computational fluid dynamics (CFD) tool CREATETM -AV HELIOS is used to investigate the interactional aerodynamics of the XV-15 tiltrotor in this work. The full vehicle is studied in a quasi-static manner with various airspeeds, nacelle angles, and vehicle attitudes to simulate hover-to-forward flight transition. The rotor is trimmed using CFD/CSD coupling with CAMRAD II. Significant wing-on-rotor interactions are observed where the thickness and loading effects of the wing create an impulsive doublet loading on the rotor as it passes over the wings. Furthermore, the wing is shown to alter the blade–vortex interactions of the rotor at high nacelle angles. The rotor in turn noticeably alters the lift and drag characteristics of the wing. At moderate to low nacelle angles, the rotor downwash enhances the dynamic pressure primarily on the upper surface of the wing, increasing the total wing lift by up to 14%. The effect on the drag varies depending on the nacelle angle. At high nacelle angles, the rotor is shown to decrease both lift and drag of the wing by 15% and 20%, respectively. Overall, this work serves to illuminate and quantify some of the complex aerodynamic interactions that occur during the conversion maneuver of tiltrotor aircraft.