摘要: An experimental investigation was conducted at the Boeing 20-ft x 20-ft VSTOL wind tunnel to study the aerodynamic interactions of the main rotor and tail rotor of a single rotor helicopter in ground effect. The model used for thi... 展开 An experimental investigation was conducted at the Boeing 20-ft x 20-ft VSTOL wind tunnel to study the aerodynamic interactions of the main rotor and tail rotor of a single rotor helicopter in ground effect. The model used for this test was the YUH-61A UTTAS at a scale of 1/4.85 with both rotors operated at full scale tip speed. A comprehensive array of parametric data was obtained to examine the interactions between main rotor/tail, rotor/fin, and main rotor/fin for various wind azimuths and airspeeds. Extensive flow visualization records were taken to define the flow mechanisms involved. In addition, quantitative data of the flow characteristics were provided by hot film measurements. Tests were conducted at the four principal wind azimuths of 0, +90, 180, -90 degrees. Parametric sweeps of airspeed, main rotor thrust, and tail rotor thrust were studied at each yaw condition. Limited investigations of the effects of varying fin size and height above the ground supplemented the parametric sweeps for the right sideward and rearward flight conditions. The effects of tail rotor placement were also investigated for the tail rotor power critical flight condition of 35 knots sideward to the right. 收起