Aerodynamic characteristics of rigid coaxial rotor by wind tunnel test and numerical calculation

Focusing on aerodynamic characteristics of rigid coaxial rotor of a high-speed helicopter in hover and forward flight, a wind tunnel test is conducted in the 8 m x 6 m low-speed straight-flow wind tunnel of China Aerodynamics Research and Development Center. In the experiment, a 4 m diameter composite model rigid coaxial rotor is designed and manufactured, and first-order flapping frequency ratio of the blade is 1.796 to ensure sufficient stiffness at the blade root. Rotor aerodynamic performance is measured under hovering and high advance ratio conditions. Also, the numerical method is used to calculate aerodynamic characteristics in typical states of the rigid coaxial rotor for analysis purpose. The rotor lift-drag ratio and lateral lift offset in the experiment are emphatically analyzed for the rigid coaxial rotor. The results indicate that in forward flight condition, the rotor lift-drag ratio first increases and then decreases with the increment of advance ratio and lift offset. When advance ratio remains constant, with the increment of lift offset, the lift-drag ratio of rigid coaxial rotor first increases and then decreases. (C) 2019 Production and hosting by Elsevier Ltd. on behalf of Chinese Society of Aeronautics and Astronautics.