Rotor slipstream effects on aerodynamic performance of tiltrotor aircraft in airplane mode

An equivalent actuator disk model was developed by taking into consideration such factors as the blade shape, the number of blade, blade pitch and rotating speed of rotor. This technique modelled the rotor implicitly through time averaged source terms in the equations and two test cases were used to validate the actuator disk model. The three-dimensional flow field around V-22 tiltrotor aircraft in high-speed airplane mode was simulated. The characteristics of the rotor flow field were analysed and the increments of aerodynamic coefficients caused by slipstream were also presented. The results showed that the rotor slipstream altered the pressure distributions on wing surface evidently, which increased the lift coefficients up to 4.6%. Slipstream decreased the drag coefficients about 29% at 0° angle of attack. However, after 4° angle of attack, slipstream increased the drag coefficients and the maximum increment was up to 32%. The variation of the pitching moment coefficient was also 4.6%. Further studies show that rotor slipstream has greater effect on the lower surface of the horizontal tail, while making a small impact on the vertical tail.